Where does the bug appear (feature/product)?
Cursor IDE
Describe the Bug
Upon opening Cursor, the IDE (agents window) is so slow it’s unsuable.
Steps to Reproduce
Not sure how to repro. I have at least 10 pending agent threads across different workspaces
Expected Behavior
It’s as performant as it was yesterday
Operating System
MacOS
Version Information
Version: 3.3.28
VSCode Version: 1.105.1
Commit: e64b4f5f409b4d92c952bf936c243894a315db10
Date: 2026-05-08T06:09:12.665Z
Layout: glass
Build Type: Stable
Release Track: Nightly
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Darwin arm64 23.5.0
Does this stop you from using Cursor
Yes - Cursor is unusable
Looks like Cursor can handle +100k changed lines in the diff?
When I open this workspace Cursor stops to a crawl
Hey man, if you have been running cursor for a while (both like.. on a single run and since a long time) a bit of cleaning around can totally fix this problem. How many plugins and skill do you have? If you don’t use them all, or have some outdated ones, cleaning those can fix those long CPU holds, you can also just ask cursor to do so.
I have all plugins and mcps deactivated. I only activate them when I need them (which I don’t understand, I think I shouldn’t have to pay a price in context when I just want to easily activate a plugin on a given conversation). Also did a skill pruning last week. I’m pretty sure that’s not the issue. The last message is the clue imo
This is a known bug with the Glass sidebar. When a workspace has a very large number of uncommitted changes (your 92 files / +136K lines), the sidebar row subscriptions scale with the change set size and aren’t capped. Combined with 10+ agent threads, it overwhelms the renderer.
Our team is tracking this and working on a fix (capping the per-row work and virtualizing the sidebar).
In the meantime, two workarounds:
-
Commit or stash the large change set in the affected workspace before opening Cursor. The sidebar performance scales with uncommitted diff size, so reducing it should help immediately.
-
Close agent threads you’re not actively using. Each mounted sidebar row adds subscription cost, so fewer visible agents = less pressure on the renderer.
Let me know if either of those helps, or if the issue persists even with a smaller diff.
