diff --git a/crates/signed_git/src/lib.rs b/crates/signed_git/src/lib.rs
index 17c16f7..b2cd14c 100644
--- a/crates/signed_git/src/lib.rs
+++ b/crates/signed_git/src/lib.rs
@@ -2,6 +2,7 @@
 //!
 //! All functions may block; call them inside `cx.background_spawn`.
 
+use std::collections::HashSet;
 use std::io::Write;
 use std::path::{Path, PathBuf};
 use std::process::{Command, Stdio};
@@ -140,6 +141,11 @@ fn sanitize_path_component(id: &str) -> String {
     sanitized
 }
 
+/// In-memory object cache for history walks (see [`open_with_cache`]).
+/// Without one, every walk re-decodes the same commit objects from the
+/// object database.
+const OBJECT_CACHE_BYTES: usize = 64 * 1024 * 1024;
+
 /// Metadata of a commit, as shown in the repository browser's file header.
 #[derive(Debug, Clone)]
 pub struct FileCommit {
@@ -222,6 +228,26 @@ pub fn find_readme(repo: &gix::Repository) -> Result<Option<PathBuf>> {
         .and_then(|path| path.strip_prefix(workdir).ok().map(Path::to_path_buf)))
 }
 
+/// Open the repository at `workdir` with an in-memory object cache sized for
+/// history walks.
+fn open_with_cache(workdir: &Path) -> Result<gix::Repository> {
+    let mut repo = gix::open(workdir)?;
+    repo.object_cache_size_if_unset(OBJECT_CACHE_BYTES);
+    Ok(repo)
+}
+
+/// A [`FileCommit`] from a walk commit: author, message title and shortened id.
+fn file_commit(commit: &gix::Commit<'_>) -> Result<FileCommit> {
+    let author = commit.author()?;
+    let message = commit.message()?;
+    Ok(FileCommit {
+        id: commit.id().shorten_or_id().to_string(),
+        summary: String::from_utf8_lossy(message.title).trim().to_string(),
+        author: String::from_utf8_lossy(author.name).trim().to_string(),
+        time: author.time()?.seconds,
+    })
+}
+
 /// Find the most recent commit that changed `rel` (a path relative to the
 /// worktree), like `git log -1 -- <rel>` does for non-merge commits.
 ///
@@ -230,56 +256,110 @@ pub fn find_readme(repo: &gix::Repository) -> Result<Option<PathBuf>> {
 /// changed the file through its second parent is therefore not reported.
 /// Returns `Ok(None)` if no commit touched the file (e.g. untracked files).
 pub fn last_commit(repo: &gix::Repository, rel: &Path) -> Result<Option<FileCommit>> {
+    let rel = rel.to_path_buf();
+    Ok(last_commits(repo, std::slice::from_ref(&rel))?
+        .into_iter()
+        .next()
+        .map(|(_, commit)| commit))
+}
+
+/// Newest commit touching each of `rels` (relative to the worktree), like
+/// `git log -1 -- <rel>` per path, found in a single history walk: every
+/// commit is decoded once and shared across all paths. Paths without any
+/// commit (e.g. untracked files) are absent from the result.
+pub fn worktree_last_commits(
+    workdir: &Path,
+    rels: &[PathBuf],
+) -> Result<Vec<(PathBuf, FileCommit)>> {
+    last_commits(&open_with_cache(workdir)?, rels)
+}
+
+/// The walk behind [`last_commit`] and [`worktree_last_commits`], stopping as
+/// soon as every pending path has its commit.
+fn last_commits(repo: &gix::Repository, rels: &[PathBuf]) -> Result<Vec<(PathBuf, FileCommit)>> {
     use gix::traverse::commit::simple::CommitTimeOrder;
 
-    let head = repo.head_id()?;
+    let Some(head) = repo.head_id().ok() else {
+        return Ok(Vec::new());
+    };
+
+    // De-duplicate while preserving order.
+    let mut pending: Vec<PathBuf> = Vec::with_capacity(rels.len());
+    let mut seen: HashSet<&Path> = HashSet::with_capacity(rels.len());
+    for rel in rels {
+        if seen.insert(rel.as_path()) {
+            pending.push(rel.clone());
+        }
+    }
+
     let walk = repo
         .rev_walk([head])
         .sorting(gix::revision::walk::Sorting::ByCommitTime(
             CommitTimeOrder::NewestFirst,
         ));
 
+    let mut found = Vec::new();
     for info in walk.all()? {
+        if pending.is_empty() {
+            break;
+        }
         let info = info?;
         let commit = info.object()?;
-        let blob = commit.tree()?.lookup_entry_by_path(rel)?;
-        let parent_blob = match info.parent_ids().next() {
-            Some(parent) => parent
-                .object()?
-                .into_commit()
-                .tree()?
-                .lookup_entry_by_path(rel)?,
+        let tree = commit.tree()?;
+        let parent_tree = match info.parent_ids().next() {
+            Some(parent) => Some(parent.object()?.into_commit().tree()?),
             None => None,
         };
 
-        if blob.map(|entry| entry.id().detach()) != parent_blob.map(|entry| entry.id().detach()) {
-            let author = commit.author()?;
-            let message = commit.message()?;
-            return Ok(Some(FileCommit {
-                id: commit.id().shorten_or_id().to_string(),
-                summary: String::from_utf8_lossy(message.title).trim().to_string(),
-                author: String::from_utf8_lossy(author.name).trim().to_string(),
-                time: author.time()?.seconds,
-            }));
+        // Compare each still-unresolved path against this commit and its
+        // first parent; resolved paths leave the pending set.
+        let mut ix = 0;
+        while ix < pending.len() {
+            let rel = &pending[ix];
+            let blob = tree.lookup_entry_by_path(rel)?;
+            let parent_blob = match &parent_tree {
+                Some(tree) => tree.lookup_entry_by_path(rel)?,
+                None => None,
+            };
+
+            if blob.map(|entry| entry.id().detach()) != parent_blob.map(|entry| entry.id().detach())
+            {
+                found.push((rel.clone(), file_commit(&commit)?));
+                pending.swap_remove(ix);
+            } else {
+                ix += 1;
+            }
         }
     }
 
-    Ok(None)
+    Ok(found)
 }
 
-/// Like [`last_commit`], but opens the repository located at `workdir`
-/// (for non-bare clones the clone root is the worktree) first.
-pub fn worktree_last_commit(workdir: &Path, rel: &Path) -> Result<Option<FileCommit>> {
-    last_commit(&gix::open(workdir)?, rel)
+/// Cap on [`CommitList::commits`]: the virtual list renders a window at a
+/// time and the tab badge shows the real count, so a huge history is never
+/// fully materialized in memory.
+pub const MAX_LISTED_COMMITS: usize = 20_000;
+
+/// Commits reachable from `HEAD`, newest first, possibly capped: `commits`
+/// holds at most [`MAX_LISTED_COMMITS`] entries and `total` is the real
+/// count (for the tab badge).
+pub struct CommitList {
+    /// Number of commits reachable from HEAD.
+    pub total: usize,
+    /// Newest commits, capped at [`MAX_LISTED_COMMITS`].
+    pub commits: Vec<FileCommit>,
 }
 
 /// All commits reachable from `HEAD`, newest first, with author and summary.
-/// Returns `Ok(vec![])` for a repository without any commits yet.
-pub fn all_commits(repo: &gix::Repository) -> Result<Vec<FileCommit>> {
+/// Returns an empty list for a repository without any commits yet.
+pub fn all_commits(repo: &gix::Repository) -> Result<CommitList> {
     use gix::traverse::commit::simple::CommitTimeOrder;
 
     let Some(head) = repo.head_id().ok() else {
-        return Ok(Vec::new());
+        return Ok(CommitList {
+            total: 0,
+            commits: Vec::new(),
+        });
     };
     let walk = repo
         .rev_walk([head])
@@ -288,25 +368,21 @@ pub fn all_commits(repo: &gix::Repository) -> Result<Vec<FileCommit>> {
         ));
 
     let mut commits = Vec::new();
+    let mut total = 0;
     for info in walk.all()? {
         let info = info?;
-        let commit = info.object()?;
-        let author = commit.author()?;
-        let message = commit.message()?;
-        commits.push(FileCommit {
-            id: commit.id().shorten_or_id().to_string(),
-            summary: String::from_utf8_lossy(message.title).trim().to_string(),
-            author: String::from_utf8_lossy(author.name).trim().to_string(),
-            time: author.time()?.seconds,
-        });
+        total += 1;
+        if commits.len() < MAX_LISTED_COMMITS {
+            commits.push(file_commit(&info.object()?)?);
+        }
     }
-    Ok(commits)
+    Ok(CommitList { total, commits })
 }
 
 /// Like [`all_commits`], but opens the repository located at `workdir`
 /// (for non-bare clones the clone root is the worktree) first.
-pub fn worktree_all_commits(workdir: &Path) -> Result<Vec<FileCommit>> {
-    all_commits(&gix::open(workdir)?)
+pub fn worktree_all_commits(workdir: &Path) -> Result<CommitList> {
+    all_commits(&open_with_cache(workdir)?)
 }
 
 /// The commit HEAD points to, like `git log -1`. Returns `Ok(None)` for a
@@ -328,7 +404,7 @@ pub fn head_commit(repo: &gix::Repository) -> Result<Option<FileCommit>> {
 
 /// Short names of local branches (`refs/heads/*`), sorted alphabetically.
 pub fn worktree_branches(workdir: &Path) -> Result<Vec<String>> {
-    let repo = gix::open(workdir)?;
+    let repo = open_with_cache(workdir)?;
     let mut names = Vec::new();
     for reference in repo.references()?.local_branches()? {
         let reference = reference.map_err(|error| anyhow::anyhow!("{error}"))?;
@@ -340,7 +416,7 @@ pub fn worktree_branches(workdir: &Path) -> Result<Vec<String>> {
 
 /// Short names of tags (`refs/tags/*`), sorted alphabetically.
 pub fn worktree_tags(workdir: &Path) -> Result<Vec<String>> {
-    let repo = gix::open(workdir)?;
+    let repo = open_with_cache(workdir)?;
     let mut names = Vec::new();
     for reference in repo.references()?.tags()? {
         let reference = reference.map_err(|error| anyhow::anyhow!("{error}"))?;
@@ -377,7 +453,7 @@ pub struct WorktreeSnapshot {
 /// Snapshot the worktree after a branch/tag switch: entries, README, the
 /// branch HEAD points to and its commit, opening the repository once.
 pub fn worktree_snapshot(workdir: &Path) -> Result<WorktreeSnapshot> {
-    let repo = gix::open(workdir)?;
+    let repo = open_with_cache(workdir)?;
     let readme_path = find_readme(&repo)?;
     let readme = match &readme_path {
         Some(path) => worktree_read(&repo, path)?,
@@ -448,6 +524,8 @@ fn collect_entries(root: &Path, dir: &Path, out: &mut Vec<(PathBuf, bool)>) -> R
 
 #[cfg(test)]
 mod tests {
+    use std::collections::HashMap;
+
     use nostr::prelude::*;
     use signed_core::repo_addr;
 
@@ -601,12 +679,13 @@ mod tests {
         std::fs::write(dir.path().join("b.txt"), b"b").expect("write");
         commit_all(&repo, "third");
 
-        let commits = all_commits(&repo).expect("commits");
-        let mut summaries: Vec<&str> = commits.iter().map(|c| c.summary.as_str()).collect();
+        let list = all_commits(&repo).expect("commits");
+        assert_eq!(list.total, 3);
+        let mut summaries: Vec<&str> = list.commits.iter().map(|c| c.summary.as_str()).collect();
         summaries.sort();
         assert_eq!(summaries, vec!["initial", "second", "third"]);
         assert!(
-            commits
+            list.commits
                 .iter()
                 .all(|c| c.author == "Test Author" && !c.id.is_empty() && c.time > 0)
         );
@@ -616,7 +695,9 @@ mod tests {
     fn all_commits_returns_empty_without_head() {
         let (_dir, repo) = fixture(&[("a.txt", b"one")]);
 
-        assert!(all_commits(&repo).expect("commits").is_empty());
+        let list = all_commits(&repo).expect("commits");
+        assert!(list.commits.is_empty());
+        assert_eq!(list.total, 0);
     }
 
     #[test]
@@ -664,6 +745,35 @@ mod tests {
         assert!(commit.summary.starts_with("Merge branch"));
     }
 
+    #[test]
+    fn last_commits_batches_multiple_paths() {
+        let (dir, repo) = fixture(&[("a.txt", b"one"), ("b.txt", b"b")]);
+        commit_all(&repo, "initial");
+
+        std::fs::write(dir.path().join("a.txt"), b"two").expect("write");
+        commit_all(&repo, "change a");
+        std::fs::write(dir.path().join("b.txt"), b"bb").expect("write");
+        commit_all(&repo, "change b");
+
+        let found = worktree_last_commits(
+            dir.path(),
+            &[
+                PathBuf::from("a.txt"),
+                PathBuf::from("b.txt"),
+                // Untracked paths are simply absent from the result.
+                PathBuf::from("missing.txt"),
+            ],
+        )
+        .expect("commits");
+        let by_path: HashMap<&Path, &FileCommit> = found
+            .iter()
+            .map(|(path, commit)| (path.as_path(), commit))
+            .collect();
+        assert_eq!(by_path.len(), 2);
+        assert_eq!(by_path[Path::new("a.txt")].summary, "change a");
+        assert_eq!(by_path[Path::new("b.txt")].summary, "change b");
+    }
+
     #[test]
     fn find_readme_prefers_markdown() {
         let (_dir, repo) = fixture(&[("readme.txt", b"txt"), ("README.md", b"md")]);
diff --git a/crates/signed_state/src/repo.rs b/crates/signed_state/src/repo.rs
index baecad4..0202456 100644
--- a/crates/signed_state/src/repo.rs
+++ b/crates/signed_state/src/repo.rs
@@ -135,6 +135,7 @@ impl RepoStore {
             })
         });
 
+        self.tasks.retain(|task| !task.is_ready());
         self.tasks.push(task);
     }
 
@@ -201,6 +202,7 @@ impl RepoStore {
             ))
         });
 
+        self.tasks.retain(|task| !task.is_ready());
         self.tasks.push(cx.spawn(async move |this, cx| {
             let (announcement, state, issues, patches, pull_requests, statuses) = match work.await {
                 Ok(data) => data,
diff --git a/crates/workspace/src/views/repo_detail/browser.rs b/crates/workspace/src/views/repo_detail/browser.rs
index 5429e67..2df4c47 100644
--- a/crates/workspace/src/views/repo_detail/browser.rs
+++ b/crates/workspace/src/views/repo_detail/browser.rs
@@ -20,6 +20,10 @@ use super::helpers::{code_language, is_markdown_path, placeholder};
 const TREE_WIDTH: f32 = 240.;
 /// Files larger than this are not previewed.
 pub(super) const MAX_PREVIEW_BYTES: usize = 1024 * 1024;
+/// Preview cache caps: at most this many files (or this many text bytes)
+/// are kept in memory at once; the oldest previews are evicted beyond that.
+pub(super) const MAX_PREVIEWED_FILES: usize = 32;
+pub(super) const MAX_PREVIEW_CACHE_BYTES: usize = 8 * 1024 * 1024;
 
 /// Preview state of a browsed file.
 pub(super) enum FileContent {
diff --git a/crates/workspace/src/views/repo_detail/commits.rs b/crates/workspace/src/views/repo_detail/commits.rs
index 89d83d3..c1b051f 100644
--- a/crates/workspace/src/views/repo_detail/commits.rs
+++ b/crates/workspace/src/views/repo_detail/commits.rs
@@ -72,7 +72,7 @@ impl RepoDetailView {
     /// Full-height body of the Commits tab: all commits in a virtual
     /// list, or a status message while loading / when there are none.
     pub(super) fn render_commits_tab(&mut self, cx: &mut Context<Self>) -> AnyElement {
-        let Some(commits) = self.all_commits.clone() else {
+        let Some(list) = self.all_commits.as_ref() else {
             return if self.loading_all_commits {
                 v_flex()
                     .size_full()
@@ -85,13 +85,18 @@ impl RepoDetailView {
             };
         };
 
-        if commits.is_empty() {
+        if list.commits.is_empty() {
             return placeholder("No commits found", cx);
         }
 
+        // Copy only the values the element tree needs; the list itself is
+        // borrowed inside the renderer below instead of being cloned per
+        // frame (a full history can be tens of thousands of commits).
         let view = cx.entity().clone();
         let sizes = self.item_sizes.clone();
         let scroll_handle = self.scroll_handle.clone();
+        let shown = list.commits.len();
+        let total = list.total;
 
         v_flex()
             .relative()
@@ -103,17 +108,29 @@ impl RepoDetailView {
                     view,
                     "repo-commits",
                     sizes,
-                    move |_this, range, _window, cx| {
-                        let mut rows = Vec::with_capacity(range.len());
-                        for ix in range {
-                            rows.push(commit_row(ix, &commits[ix], cx));
-                        }
-                        rows
+                    move |this, range, _window, cx| {
+                        let commits = this
+                            .all_commits
+                            .as_ref()
+                            .map(|list| list.commits.as_slice())
+                            .unwrap_or(&[]);
+                        range.map(|ix| commit_row(ix, &commits[ix], cx)).collect()
                     },
                 )
                 .track_scroll(&scroll_handle)
                 .size_full(),
             )
+            .when(shown < total, |this| {
+                // The history is capped; tell the user the list is truncated.
+                this.child(
+                    div()
+                        .py_2()
+                        .w_full()
+                        .text_xs()
+                        .text_color(cx.theme().muted_foreground)
+                        .child(format!("Showing {shown} of {total} commits")),
+                )
+            })
             .child(
                 div()
                     .absolute()
diff --git a/crates/workspace/src/views/repo_detail/helpers.rs b/crates/workspace/src/views/repo_detail/helpers.rs
index cf6b7f4..93b6a6e 100644
--- a/crates/workspace/src/views/repo_detail/helpers.rs
+++ b/crates/workspace/src/views/repo_detail/helpers.rs
@@ -1,6 +1,7 @@
 //! Pure helpers for the repository detail view: file-tree building, code
 //! preview helpers and small element builders.
 
+use std::collections::HashMap;
 use std::path::{Path, PathBuf};
 
 use gpui::prelude::*;
@@ -8,43 +9,75 @@ use gpui::{AnyElement, App, div};
 use gpui_component::tree::TreeItem;
 use gpui_component::{ActiveTheme, v_flex};
 
-/// Build nested tree items from a flat, sorted (dirs-first) entry list.
-pub(super) fn build_tree_items(entries: &[PathBuf]) -> Vec<TreeItem> {
-    let mut roots: Vec<TreeItem> = Vec::new();
-
-    for entry in entries {
-        let parts: Vec<String> = entry
-            .components()
-            .map(|c| c.as_os_str().to_string_lossy().into_owned())
-            .collect();
-        insert_path(&mut roots, &parts, "");
-    }
-
-    roots
+/// A `Send` file-tree node: the tree is built on a background thread and
+/// converted into [`TreeItem`]s (which hold `Rc` state, so they cannot
+/// cross threads) on the main thread.
+pub(super) struct TreeItemSeed {
+    /// Path of the node, relative to the worktree root.
+    id: String,
+    /// File or directory name.
+    label: String,
+    children: Vec<TreeItemSeed>,
 }
 
-/// Insert `parts` (path components) into the tree rooted at `items`.
-/// `prefix` is the path of `items`' parent, used to build item ids.
-fn insert_path(items: &mut Vec<TreeItem>, parts: &[String], prefix: &str) {
-    let Some((head, rest)) = parts.split_first() else {
-        return;
-    };
-
-    let id = if prefix.is_empty() {
-        head.clone()
-    } else {
-        format!("{prefix}/{head}")
-    };
-
-    if let Some(existing) = items.iter_mut().find(|item| &*item.label == head.as_str()) {
-        insert_path(&mut existing.children, rest, &id);
-    } else {
-        let mut item = TreeItem::new(id.clone(), head.clone());
-        insert_path(&mut item.children, rest, &id);
-        items.push(item);
+impl From<TreeItemSeed> for TreeItem {
+    fn from(seed: TreeItemSeed) -> Self {
+        let mut item = TreeItem::new(seed.id, seed.label);
+        item.children = seed.children.into_iter().map(Into::into).collect();
+        item
     }
 }
 
+/// Build nested tree items from a flat, sorted (dirs-first) entry list.
+///
+/// Returns [`TreeItemSeed`]s so the build can run off the main thread; a
+/// worktree walk can yield tens of thousands of entries. Nodes live in an
+/// arena and parents are found via a path -> index map, which keeps the
+/// build linear in the number of path components.
+pub(super) fn build_tree_items(entries: &[PathBuf]) -> Vec<TreeItemSeed> {
+    // Node indices by full path, for O(1) parent lookup while inserting.
+    let mut index: HashMap<String, usize> = HashMap::new();
+    let mut nodes: Vec<(String, String, Vec<usize>)> = Vec::new();
+    let mut roots: Vec<usize> = Vec::new();
+
+    for entry in entries {
+        let mut parent: Option<usize> = None;
+        let mut path = String::new();
+        for part in entry.components() {
+            let label = part.as_os_str().to_string_lossy().into_owned();
+            path = if path.is_empty() {
+                label.clone()
+            } else {
+                format!("{path}/{label}")
+            };
+            let ix = *index.entry(path.clone()).or_insert_with(|| {
+                let ix = nodes.len();
+                nodes.push((path.clone(), label.clone(), Vec::new()));
+                match parent {
+                    Some(parent) => nodes[parent].2.push(ix),
+                    None => roots.push(ix),
+                }
+                ix
+            });
+            parent = Some(ix);
+        }
+    }
+
+    fn assemble(ix: usize, nodes: &[(String, String, Vec<usize>)]) -> TreeItemSeed {
+        let (id, label, children) = &nodes[ix];
+        TreeItemSeed {
+            id: id.clone(),
+            label: label.clone(),
+            children: children
+                .iter()
+                .map(|child| assemble(*child, nodes))
+                .collect(),
+        }
+    }
+
+    roots.iter().map(|root| assemble(*root, &nodes)).collect()
+}
+
 /// The markdown fence language for a file path, or `None` for plain text.
 ///
 /// Names are chosen so `gpui_component`'s highlighter can resolve them
@@ -174,6 +207,42 @@ mod tests {
         assert_eq!(items[0].children[0].children[0].id, "a/b/c.txt");
     }
 
+    #[test]
+    fn tree_builder_merges_shared_prefixes() {
+        // File children of a directory arrive after other directories'
+        // entries (the worktree list is dirs-first globally); the shared
+        // prefix must still resolve to one node.
+        let entries = vec![
+            PathBuf::from("a/x.txt"),
+            PathBuf::from("b/y.txt"),
+            PathBuf::from("a/z.txt"),
+        ];
+
+        let items = build_tree_items(&entries);
+        assert_eq!(items.len(), 2);
+        assert_eq!(items[0].label, "a");
+        assert_eq!(items[0].children.len(), 2);
+        assert_eq!(items[1].label, "b");
+    }
+
+    #[test]
+    fn tree_seeds_convert_to_tree_items() {
+        let entries = vec![
+            PathBuf::from("src"),
+            PathBuf::from("src/main.rs"),
+            PathBuf::from("README.md"),
+        ];
+
+        let items: Vec<TreeItem> = build_tree_items(&entries)
+            .into_iter()
+            .map(Into::into)
+            .collect();
+        assert_eq!(items.len(), 2);
+        assert_eq!(items[0].label, "src");
+        assert_eq!(items[0].children.len(), 1);
+        assert_eq!(items[0].children[0].label, "main.rs");
+    }
+
     #[test]
     fn code_language_maps_extensions_and_names() {
         assert_eq!(code_language("src/main.rs"), Some("rust"));
diff --git a/crates/workspace/src/views/repo_detail/mod.rs b/crates/workspace/src/views/repo_detail/mod.rs
index 0912548..46a00e8 100644
--- a/crates/workspace/src/views/repo_detail/mod.rs
+++ b/crates/workspace/src/views/repo_detail/mod.rs
@@ -1,4 +1,4 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::{HashMap, HashSet, VecDeque};
 use std::path::{Component, Path, PathBuf};
 use std::rc::Rc;
 
@@ -16,19 +16,22 @@ use gpui_component::menu::PopupMenuItem;
 use gpui_component::searchable_list::SearchableVec;
 use gpui_component::tab::{Tab, TabBar};
 use gpui_component::tag::Tag;
-use gpui_component::tree::TreeState;
+use gpui_component::tree::{TreeItem, TreeState};
 use gpui_component::{
     ActiveTheme, Icon, IconName, Sizable, StyledExt, VirtualListScrollHandle, h_flex, v_flex,
 };
 use signed_core::Announcement;
-use signed_git::FileCommit;
+use signed_git::{CommitList, FileCommit};
 use signed_state::{GitStore, RepoStore};
 
 mod browser;
 mod commits;
 mod helpers;
 
-use browser::{CodeView, FileContent, MAX_PREVIEW_BYTES, MarkdownView};
+use browser::{
+    CodeView, FileContent, MAX_PREVIEW_BYTES, MAX_PREVIEW_CACHE_BYTES, MAX_PREVIEWED_FILES,
+    MarkdownView,
+};
 use commits::COMMIT_ROW_HEIGHT;
 use helpers::{build_tree_items, is_markdown_path};
 
@@ -44,10 +47,16 @@ enum RefKind {
 /// Detail view of a repository: header, stats, a file explorer with README
 /// preview (cloned from the announcement's `clone` URLs), and metadata.
 pub struct RepoDetailView {
-    /// Live per-repository store, refreshed from the local database.
-    store: Entity<RepoStore>,
-    /// Snapshot taken at open time, shown until the store's first refresh completes.
+    /// Snapshot taken at open time, shown until the store's first refresh
+    /// completes (and as a fallback while the store has no announcement).
     initial: Announcement,
+    /// Latest announcement from the store, cached so `render` (which runs
+    /// every frame) does not re-read and re-clone the store's copy.
+    announcement: Option<Announcement>,
+    /// Relay/web URLs of [`Self::announcement`] as display strings, for the
+    /// header dropdowns; `Rc` so the menu builders clone cheaply per frame.
+    relays: Rc<Vec<SharedString>>,
+    web: Rc<Vec<SharedString>>,
     /// File explorer state (worktree of the local clone).
     tree_state: Entity<TreeState>,
     /// Root of the local clone, for reading files on demand.
@@ -60,17 +69,25 @@ pub struct RepoDetailView {
     /// Currently previewed file (relative path) and its contents.
     selected_file: Option<SharedString>,
     files: HashMap<String, FileContent>,
+    /// Paths of cached previews, oldest first; feeds the eviction caps in
+    /// [`Self::evict_previews`].
+    file_order: VecDeque<String>,
+    /// Total text bytes held by [`Self::files`].
+    preview_bytes: usize,
     /// Reads in flight, to avoid duplicate loads.
     loading_files: HashSet<String>,
     /// Latest commit touching a previewed file (or the README), keyed by path.
     commits: HashMap<String, FileCommit>,
-    /// Commit queries in flight, to avoid duplicate loads.
-    loading_commits: HashSet<String>,
+    /// Paths queued for the next batched commit query (see [`Self::load_commits`]).
+    pending_commits: Vec<String>,
+    /// A batched commit query is in flight.
+    loading_commits: bool,
     /// Active header tab: 0 = Files (tree), 1 = Commits.
     active_tab: usize,
-    /// All commits reachable from HEAD, newest first; `None` until the
-    /// walk finishes (or fails).
-    all_commits: Option<Vec<FileCommit>>,
+    /// Commits reachable from HEAD, newest first; `None` until the walk
+    /// finishes (or fails). `commits` may be capped by
+    /// [`CommitList`]; `total` feeds the tab badge.
+    all_commits: Option<CommitList>,
     /// Commit walk in flight.
     loading_all_commits: bool,
     /// Virtual list state of the Commits tab.
@@ -90,10 +107,13 @@ pub struct RepoDetailView {
     /// Bumped on every branch/tag switch; in-flight loads tagged with an
     /// older generation are discarded when they complete.
     ref_generation: u64,
-    /// Subscriptions keeping the selectors' confirm events alive.
-    _subscriptions: Vec<Subscription>,
     focus_handle: FocusHandle,
+    /// In-flight tasks; finished tasks are pruned on every push, so the vec
+    /// stays bounded by the number of concurrent loads.
     tasks: Vec<Task<Result<(), Error>>>,
+    /// Subscriptions keeping the selectors' confirm events and the store's
+    /// refreshes alive.
+    _subscriptions: Vec<Subscription>,
 }
 
 impl RepoDetailView {
@@ -121,7 +141,36 @@ impl RepoDetailView {
             .searchable(true)
         });
 
-        let subscriptions = vec![
+        // Cache the announcement for the header: the store only changes it
+        // during debounced refreshes, but `render` runs every frame. The
+        // observe subscription owns the store for the view's lifetime.
+        let subscription = cx.observe(&store, |this, store, cx| {
+            let fresh = store.read(cx).announcement.clone();
+            if this.announcement == fresh {
+                return;
+            }
+            this.announcement = fresh;
+            // The header falls back to the open-time snapshot while the
+            // store has no announcement; keep its dropdown lists in sync.
+            let announcement = this.announcement.as_ref().unwrap_or(&this.initial);
+            this.relays = Rc::new(
+                announcement
+                    .relays
+                    .iter()
+                    .map(|relay| relay.to_string().into())
+                    .collect(),
+            );
+            this.web = Rc::new(
+                announcement
+                    .web
+                    .iter()
+                    .map(|url| url.to_string().into())
+                    .collect(),
+            );
+            cx.notify();
+        });
+
+        let mut subscriptions = vec![
             cx.subscribe_in(&branch_select, window, |this, _state, event, window, cx| {
                 // `Change` fires only when the selection actually changed
                 // (picking the already-selected branch emits nothing), so a
@@ -140,15 +189,35 @@ impl RepoDetailView {
                 }
             }),
         ];
+        subscriptions.push(subscription);
 
         // Defer loading the repository until the window is ready.
         cx.defer_in(window, |this, window, cx| {
             this.load_repo(window, cx);
         });
 
+        // Header dropdowns of the open-time snapshot, until the store's
+        // first refresh replaces them.
+        let relays = Rc::new(
+            initial
+                .relays
+                .iter()
+                .map(|relay| relay.to_string().into())
+                .collect(),
+        );
+        let web = Rc::new(
+            initial
+                .web
+                .iter()
+                .map(|url| url.to_string().into())
+                .collect(),
+        );
+
         Self {
-            store,
             initial,
+            announcement: None,
+            relays,
+            web,
             tree_state,
             worktree: None,
             md: None,
@@ -156,9 +225,12 @@ impl RepoDetailView {
             readme_name: None,
             selected_file: None,
             files: HashMap::new(),
+            file_order: VecDeque::new(),
+            preview_bytes: 0,
             loading_files: HashSet::new(),
             commits: HashMap::new(),
-            loading_commits: HashSet::new(),
+            pending_commits: Vec::new(),
+            loading_commits: false,
             active_tab: 0,
             all_commits: None,
             loading_all_commits: false,
@@ -190,6 +262,10 @@ impl RepoDetailView {
         let load = cx.background_spawn(async move {
             let repo = cache.ensure_clone(&addr, &clone_urls)?;
             let entries = signed_git::worktree_entries(&repo)?;
+            // The tree is built off the main thread; the seeds are plain
+            // owned strings and convert to `TreeItem`s (which hold `Rc`
+            // state) on the main thread.
+            let tree = build_tree_items(&entries);
             let readme_path = signed_git::find_readme(&repo)?;
             let readme = match &readme_path {
                 Some(path) => signed_git::worktree_read(&repo, path)?,
@@ -209,7 +285,7 @@ impl RepoDetailView {
             let head_commit = signed_git::head_commit(&repo).unwrap_or(None);
 
             Ok::<_, Error>((
-                entries,
+                tree,
                 readme_path,
                 readme,
                 worktree,
@@ -226,7 +302,7 @@ impl RepoDetailView {
             this.update_in(cx, |this, window, cx| {
                 match result {
                     Ok((
-                        entries,
+                        tree,
                         readme_path,
                         readme,
                         Some(worktree),
@@ -238,7 +314,10 @@ impl RepoDetailView {
                         this.worktree = Some(worktree);
                         this.head_commit = head_commit;
                         this.tree_state.update(cx, |state, cx| {
-                            state.set_items(build_tree_items(&entries), cx);
+                            state.set_items(
+                                tree.into_iter().map(Into::into).collect::<Vec<TreeItem>>(),
+                                cx,
+                            );
                         });
 
                         // Populate the branch/tag selectors with the local
@@ -280,7 +359,7 @@ impl RepoDetailView {
             Ok(())
         });
 
-        self.tasks.push(task);
+        self.track(task);
     }
 
     /// Preview the file at `path` (relative to the worktree root).
@@ -321,20 +400,24 @@ impl RepoDetailView {
             let content = cx
                 .background_spawn(async move {
                     let full = worktree.join(&path_for_read);
+                    // Refuse oversized files before reading them: reading a
+                    // multi-gigabyte file just to classify it as too large
+                    // would waste the disk and memory bandwidth.
+                    let metadata = match std::fs::metadata(&full) {
+                        Ok(metadata) => metadata,
+                        Err(error) => return Err(anyhow::anyhow!("{}", error)),
+                    };
+                    if metadata.len() > MAX_PREVIEW_BYTES as u64 {
+                        return Ok(FileContent::TooLarge);
+                    }
                     let bytes = match std::fs::read(&full) {
                         Ok(bytes) => bytes,
                         Err(error) => return Err(anyhow::anyhow!("{}", error)),
                     };
-
-                    let kind = if bytes.len() > MAX_PREVIEW_BYTES {
-                        FileContent::TooLarge
-                    } else {
-                        match String::from_utf8(bytes) {
-                            Ok(text) => FileContent::Text(text),
-                            Err(_) => FileContent::Binary,
-                        }
-                    };
-                    Ok::<_, Error>(kind)
+                    match String::from_utf8(bytes) {
+                        Ok(text) => Ok(FileContent::Text(text)),
+                        Err(_) => Ok(FileContent::Binary),
+                    }
                 })
                 .await;
 
@@ -361,8 +444,11 @@ impl RepoDetailView {
                                     this.set_code(path.clone().into(), text, window, cx);
                                 }
                             }
+                            this.preview_bytes += text.len();
                         }
-                        this.files.insert(path, kind);
+                        this.files.insert(path.clone(), kind);
+                        this.file_order.push_back(path);
+                        this.evict_previews();
                     }
                     Err(error) => {
                         this.files
@@ -375,38 +461,64 @@ impl RepoDetailView {
             Ok(())
         });
 
-        self.tasks.push(task);
+        self.track(task);
     }
 
-    /// Query the latest commit touching `path` on a background task and cache
-    /// it in [`Self::commits`], for the file header in the content column.
+    /// Queue `path` for the per-file commit query; requests are batched into
+    /// one history walk (see [`Self::load_commits`]).
     fn load_commit(&mut self, path: &str, cx: &mut Context<Self>) {
-        if self.commits.contains_key(path) || self.loading_commits.contains(path) {
+        if self.commits.contains_key(path) || self.pending_commits.iter().any(|p| p == path) {
+            return;
+        }
+        self.pending_commits.push(path.to_string());
+        if !self.loading_commits {
+            self.load_commits(cx);
+        }
+    }
+
+    /// Walk history once for every queued path on a background task, and
+    /// cache the latest commit touching each of them in [`Self::commits`]
+    /// (for the file header in the content column).
+    ///
+    /// Batching shares one walk (and its object decodes) across all paths
+    /// queued while the previous walk was in flight, instead of walking the
+    /// full history per file.
+    fn load_commits(&mut self, cx: &mut Context<Self>) {
+        if self.pending_commits.is_empty() || self.loading_commits {
             return;
         }
         let Some(worktree) = self.worktree.clone() else {
+            self.pending_commits.clear();
             return;
         };
 
-        self.loading_commits.insert(path.to_string());
-        let path = path.to_string();
+        self.loading_commits = true;
+        let paths = std::mem::take(&mut self.pending_commits);
         let generation = self.ref_generation;
 
         let task = cx.spawn(async move |this, cx| {
-            let path_for_query = path.clone();
+            let rels: Vec<PathBuf> = paths.iter().map(PathBuf::from).collect();
             let result = cx
-                .background_spawn(async move {
-                    signed_git::worktree_last_commit(&worktree, Path::new(&path_for_query))
-                })
+                .background_spawn(
+                    async move { signed_git::worktree_last_commits(&worktree, &rels) },
+                )
                 .await;
 
             this.update(cx, |this, cx| {
                 if generation != this.ref_generation {
                     return;
                 }
-                this.loading_commits.remove(&path);
-                if let Ok(Some(commit)) = result {
-                    this.commits.insert(path, commit);
+                this.loading_commits = false;
+                if let Ok(found) = result {
+                    for (path, commit) in found {
+                        this.commits
+                            .insert(path.to_string_lossy().into_owned(), commit);
+                    }
+                }
+                // Paths queued while the walk was in flight start the next
+                // batch.
+                if !this.pending_commits.is_empty() {
+                    this.load_commits(cx);
                 }
                 cx.notify();
             })?;
@@ -414,11 +526,12 @@ impl RepoDetailView {
             Ok(())
         });
 
-        self.tasks.push(task);
+        self.track(task);
     }
 
     /// Walk all commits reachable from HEAD on a background task, for the
-    /// Commits tab and its total-count badge.
+    /// Commits tab and its total-count badge. The list is capped by
+    /// [`CommitList`]; only the newest commits are materialized.
     fn load_all_commits(&mut self, cx: &mut Context<Self>) {
         if self.loading_all_commits || self.all_commits.is_some() {
             return;
@@ -440,10 +553,10 @@ impl RepoDetailView {
                 if generation != this.ref_generation {
                     return;
                 }
-                if let Ok(commits) = result {
-                    let count = commits.len();
+                if let Ok(list) = result {
+                    let count = list.commits.len();
                     this.item_sizes = Rc::new(vec![size(px(0.), px(COMMIT_ROW_HEIGHT)); count]);
-                    this.all_commits = Some(commits);
+                    this.all_commits = Some(list);
                 }
                 this.loading_all_commits = false;
                 cx.notify();
@@ -452,7 +565,7 @@ impl RepoDetailView {
             Ok(())
         });
 
-        self.tasks.push(task);
+        self.track(task);
     }
 
     /// Check out `name` (a branch or tag picked in the header) and refresh
@@ -524,7 +637,7 @@ impl RepoDetailView {
             Ok(())
         });
 
-        self.tasks.push(task);
+        self.track(task);
     }
 
     /// Restore a selector to `previous`, or clear it (after a failed switch).
@@ -589,27 +702,38 @@ impl RepoDetailView {
 
         let task = cx.spawn(async move |this, cx| {
             let result = cx
-                .background_spawn(async move { signed_git::worktree_snapshot(&worktree) })
+                .background_spawn(async move {
+                    let snapshot = signed_git::worktree_snapshot(&worktree)?;
+                    // Build the tree off the main thread, like [`Self::load_repo`].
+                    let tree = build_tree_items(&snapshot.entries);
+                    Ok::<_, Error>((snapshot, tree))
+                })
                 .await;
 
             this.update(cx, |this, cx| {
                 this.switching_ref = false;
                 match result {
-                    Ok(snapshot) => {
+                    Ok((snapshot, tree)) => {
                         this.head_commit = snapshot.head_commit;
                         // Rebuild the tree from scratch: entries of the
                         // previous branch are gone, and with them the
                         // expansion state.
                         this.tree_state.update(cx, |state, cx| {
-                            state.set_items(build_tree_items(&snapshot.entries), cx);
+                            state.set_items(
+                                tree.into_iter().map(Into::into).collect::<Vec<TreeItem>>(),
+                                cx,
+                            );
                         });
 
                         // Drop cached previews and commits of the old branch.
                         this.selected_file = None;
                         this.files.clear();
+                        this.file_order.clear();
+                        this.preview_bytes = 0;
                         this.loading_files.clear();
                         this.commits.clear();
-                        this.loading_commits.clear();
+                        this.pending_commits.clear();
+                        this.loading_commits = false;
                         this.md = None;
                         this.code = None;
                         this.readme_name = None;
@@ -640,8 +764,45 @@ impl RepoDetailView {
             Ok(())
         });
 
+        self.track(task);
+    }
+
+    /// Track `task` until it completes; finished tasks are pruned on every
+    /// push so the vec stays bounded by the number of in-flight loads.
+    fn track(&mut self, task: Task<Result<(), Error>>) {
+        self.tasks.retain(|task| !task.is_ready());
         self.tasks.push(task);
     }
+
+    /// Drop the oldest previews beyond the cache caps, keeping the currently
+    /// selected file. The parsed editor state of an evicted file is dropped
+    /// along with its entry, so re-opening it re-parses on a background task.
+    fn evict_previews(&mut self) {
+        while (self.files.len() > MAX_PREVIEWED_FILES
+            || self.preview_bytes > MAX_PREVIEW_CACHE_BYTES)
+            && self.file_order.len() > 1
+        {
+            let path = self.file_order.pop_front().expect("non-empty");
+            if Some(path.as_str()) == self.selected_file.as_deref() {
+                self.file_order.push_back(path);
+                continue;
+            }
+            if let Some(FileContent::Text(text)) = self.files.remove(&path) {
+                self.preview_bytes -= text.len();
+            }
+            if self.md.as_ref().map(|md| md.path.as_deref()) == Some(Some(path.as_str())) {
+                self.md = None;
+            }
+            if self
+                .code
+                .as_ref()
+                .is_some_and(|code| code.path.as_ref() == path.as_str())
+            {
+                self.code = None;
+            }
+            self.commits.remove(&path);
+        }
+    }
 }
 
 impl Panel for RepoDetailView {
@@ -649,13 +810,8 @@ impl Panel for RepoDetailView {
         "repo_detail"
     }
 
-    fn title(&mut self, _window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
-        let announcement = self
-            .store
-            .read(cx)
-            .announcement
-            .clone()
-            .unwrap_or_else(|| self.initial.clone());
+    fn title(&mut self, _window: &mut Window, _cx: &mut Context<Self>) -> impl IntoElement {
+        let announcement = self.announcement.as_ref().unwrap_or(&self.initial);
 
         announcement
             .name
@@ -677,12 +833,9 @@ impl Render for RepoDetailView {
         let tree_state = self.tree_state.clone();
         let view = cx.entity().downgrade();
 
-        let announcement = self
-            .store
-            .read(cx)
-            .announcement
-            .clone()
-            .unwrap_or_else(|| self.initial.clone());
+        let announcement = self.announcement.as_ref().unwrap_or(&self.initial);
+        let relays = self.relays.clone();
+        let web = self.web.clone();
 
         let name = announcement
             .name
@@ -700,9 +853,7 @@ impl Render for RepoDetailView {
             .or_else(|| self.readme_name.clone())
             .unwrap_or_else(|| "Overview".into());
 
-        let relays = announcement.relays.clone();
-        let web = announcement.web.clone();
-        let commits_count = self.all_commits.as_ref().map(Vec::len);
+        let commits_count = self.all_commits.as_ref().map(|list| list.total);
         let worktree_empty = self.switching_ref || self.worktree.is_none();
 
         v_flex()