[noahbclarkson]

Problem

On a laptop with an integrated GPU (Ryzen/Renoir, Hyprland, 60Hz) the app felt laggy: hover feedback trailed the pointer by 50–150ms and browsing commits dropped frames. Zed, on the same gpui renderer, was smooth. Two costs were stacking up on every frame:

1. GPU: one full-window MSAA pass per path in view. gpui draws each run of paths it can't merge by rasterizing it into a full-window, 4× multisampled intermediate texture, then resolving and compositing that back. The graph drew each row's approach line, occluding ring and node dot as paths. Rows also painted 4–8px into their neighbours, which chained gpui's draw order down the list, so no two rows' paths could share a pass. A handful of visible rows meant 5–8 full-window passes per frame, about 40MB of memory traffic each, on a GPU that shares bandwidth with the CPU. Frames backed up in the GPU queue. The cost grew with window size, and hiding the graph didn't fix it.
2. CPU: the whole window was rebuilt every frame. Nothing used gpui's view caching, so a hover that changed one row's background still re-rendered, laid out (taffy) and painted every panel: ~9–10ms of main-thread time on battery.

What changes

• Graph dots and rings are quads (rgitui_graph/src/paint.rs). The approach line uses the existing lane quad. Only curves and the pinned-lane › chevron are still paths.
• Nothing a row paints leaves the row. graph_cell_mask now clips top and bottom as well as the sides. Unrounded quads are not antialiased, so lane segments in adjacent rows still meet without a seam.
• The main panels are cached views. The sidebar, graph, diff viewer, detail panel and commit panel each redraw only when that panel is notified (workspace/layout.rs).
• Globals refresh the windows. Cached views don't see globals change, so the workspace now refreshes its windows when ThemeState or SettingsState changes. Language switches and focus changes already refresh.
• Avatar images load in the resolver. gpui notifies only the first view that requested an image when it finishes loading. The resolver now starts each avatar's load itself and refreshes when it lands, so a cached graph can't miss an avatar the detail panel happened to request first.
• GraphView::set_all_loaded now notifies. It was only ever called next to methods that do, so this is robustness rather than a fix.
• Harness: a hover replay step and a hover-sweep scenario that sweeps the pointer over the sidebar, the graph rows and the window at 120Hz. Documented in docs/PERFORMANCE.md.

Visible change: the working-tree node's dashed outer ring now uses gpui's dashed border, so it has finer, lighter dashes than the previous 8 bold ones. Keeping the old dashes would add a path pass to every frame where that row is visible.

Measurements

--profile perf builds of main (cd9c4b4) and this branch, against this repository, laptop on charge, same window size. Path passes were counted with a temporary scene census in a local gpui copy, which isn't part of this PR.

Scenario	Metric	main	This PR
graph-scroll	path passes per frame	6–8	0–1
graph-scroll	dropped frames (of ~580)	32	4
graph-scroll	frame interval p95	26.1 ms	17.2 ms
graph-scroll	draw p50 (main thread)	7.8 ms	5.5 ms
hover-sweep	path passes per frame	5	1
hover-sweep	draw p50 (main thread)	10.1 ms	1.5 ms
hover-sweep	draw p95 (main thread)	11.0 ms	6.7 ms

Testing

• Tested on Windows
• Tested on macOS
• Tested on Linux (NixOS, Hyprland/Wayland, AMD Renoir iGPU)
• All existing tests pass (cargo test --workspace)
• Code passes clippy (cargo clippy --workspace --all-targets -- -D warnings)
• Code is formatted (cargo fmt --all -- --check)

Also checked:

• Layout matches. Screenshots of main and this branch line up: line joins, curves and spacing are the same. With caching on and off, the screenshots match pixel for pixel apart from antialiasing noise.
• Cached panels update live. Adding and removing an untracked file updated the cached sidebar's count (?2 → ?3 → ?2) with no interaction.
• Hover is smooth by hand on the laptop, full-screen.

Not verified end to end: the avatar preload. While testing, GitHub's search API was rate-limited, so the avatars it affects couldn't resolve on main either.

🤖 Generated with Claude Code

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Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-04T10:36:25.426846Z	220195e	PR opened

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