# \[Performance\] Cursor IDE causes severe system lag and high memory usage **URL:** \ **Category:** Bug Reports\ **Tags:** performance, crashes\ **Created:** [July 30, 2026, 1:26pm UTC](https://forum.cursor.com/t/performance-cursor-ide-causes-severe-system-lag-and-high-memory-usage/167059 "2026-07-30T13:26:21Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![juju](https://avatars.discourse-cdn.com/v4/letter/j/258eb7/32.png) [@juju](https://forum.cursor.com/u/juju)\ **Post date:** [July 30, 2026, 1:26pm UTC](https://forum.cursor.com/t/performance-cursor-ide-causes-severe-system-lag-and-high-memory-usage/167059/1 "2026-07-30T13:26:21Z")
### Where does the bug appear (feature/product)? Cursor IDE ### Describe the Bug Describe the bug: I am experiencing significant performance issues with Cursor. The application consumes an excessive amount of RAM, which leads to severe system lag and freezing, making it difficult to use ### Steps to Reproduce Open Cursor and load a medium-sized project (e.g., “midscene-ai-test-platform”). Start using the Agent feature (Cmd+I) to generate or modify code. Observe that after a few interactions, the system memory usage spikes significantly. The entire computer becomes laggy, and typing in the editor has high latency. Attempting to run diagnostics results in a “Could not collect diagnostics” error because Shell calls return no exit status. “The screenshot shows the state after I already took action. The memory usage only dropped after I closed the IDE.” ### Expected Behavior ### Screenshots / Screen Recordings ![image_178541752183321.png](https://us1.discourse-cdn.com/cursor1/original/3X/f/8/f8815f3a8a88574f6e56360a12da658e105a73c9.png) ### Operating System MacOS ### Version Information OS: macOS Sequoia 15.6 RAM: 16GB Cursor Version: 3.13.10 ### For AI issues: which model did you use? === Cursor Node Process Performance Sample (Simplified) === Process: node [PID 871] Parent: Cursor Helper (Plugin) [PID 732] Path: /Applications/Cursor.app/Contents/Resources/app/resources/helpers/node OS: macOS 15.7.3 (Apple Silicon / ARM64) Sample Time: 2026-07-30 20:41:53 (launched at 20:32:00) — Memory Usage — Physical footprint: 876.9M (peak: 959.8M) This single Cursor helper process consumed ~877MB of physical RAM. — Thread Status (All 2519 samples) — Thread\_9402 (Main): BLOCKED in kevent() — event loop not responding Thread\_9497 (DelayedTaskScheduler): BLOCKED in kevent() — no tasks being processed Thread\_9498-9501 (Worker threads x4): BLOCKED in \_\_psynch\_cvwait() — all waiting on condition variables, no work being executed Thread\_9561 (Inspector IO): BLOCKED in semaphore\_wait\_trap() Thread\_9576 (Work queue): BLOCKED in \_\_workq\_kernreturn() — idle, no work items — Key Findings — 1. ALL threads are blocked/idle — the process is in a “zombie” state, consuming ~877MB RAM but doing zero work. 2. Main thread stuck in uv\_\_io\_poll → kevent: Node.js event loop is waiting for I/O events that never arrive. 3. 4 worker threads stuck in \_\_psynch\_cvwait: Task queues are empty but threads are not terminating. 4. This is a classic memory leak + thread leak pattern: the process allocates memory and spawns threads but never cleans them up. — Top Blocked System Calls — \_\_psynch\_cvwait: 10076 samples (worker threads waiting) kevent: 5038 samples (event loop polling) \_\_workq\_kernreturn: 2519 samples (idle work queue) semaphore\_wait\_trap: 2519 samples (inspector thread) === End of Simplified Report === ### Does this stop you from using Cursor Yes - Cursor is unusable ---
**Author:** ![deanrie](https://sea3.discourse-cdn.com/cursor1/user_avatar/forum.cursor.com/deanrie/32/1263_2.png) [@deanrie](https://forum.cursor.com/u/deanrie)\ **Post date:** [July 30, 2026, 4:05pm UTC](https://forum.cursor.com/t/performance-cursor-ide-causes-severe-system-lag-and-high-memory-usage/167059/5 "2026-07-30T16:05:02Z")
Hey, thanks for the detailed report and the sample, it helps. A couple clarifications on what you’re seeing. The `node` process at about 877MB, parent is Cursor Helper Plugin, is the TypeScript language server `tsserver`, not a zombie process. That memory size is normal for a medium-size project, and the blocked idle threads are just a normal idle event loop, not a leak. If you want, you can cap it via `typescript.tsserver.maxTsServerMemory`, but it likely won’t fix the main source of the lag. The memory growth and overall system pressure, your screenshot shows 13,56GB out of 16GB with 5,6GB compressed, is a known issue we’re tracking. During long Agent sessions, chat state slowly builds up in memory. On a 16GB Mac it eventually hits the ceiling and causes lag. I can’t share an exact timeline yet, but I’ll post an update in the thread when we have one. For now, this usually helps: - Clean the internal store, this is the biggest lever. Open Command Palette with `Cmd+Shift+P`, run Developer: Delete Old Chats… pick an age, then run GC Agent KV Blobs. This compacts the store and frees space. On a large store, GC can freeze the window for 1 to 2 minutes, that’s expected, don’t force close it. - Split long Agent work into multiple shorter chats instead of one endless session. The memory growth is tied to the accumulated state inside a single chat. - Quit Cursor with `Cmd+Q`, not the red window button. On macOS, closing the window doesn’t always stop background helper processes, and they can keep holding memory. - Restart Cursor when the system starts swapping. - Keep Cursor updated, improvements in this area ship gradually. The error Could not collect diagnostics / Shell calls return no exit status happens because under load the backend for shell commands can hang. After a restart, once the pressure drops, diagnostics should work normally again. Let me know if splitting into shorter sessions and cleaning the store helps in your case.