**Severe Lag and UI Freezing When Editing Large Files (~1000+ Lines) with Agent Enabled on Mac Mini M4**

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Hey, thanks for the detailed report. A 1 000-line file isn’t that big, and a Mac mini M4 should handle it fine, so something’s clearly off.

To narrow it down, we need a bit of diagnostics:

  1. Process Explorer: when the lag starts, open Cmd+Shift+P then run Developer: Open Process Explorer. Send a screenshot so we can see which process is using CPU (extensionHost, renderer, ptyHost, etc).

  2. Test without extensions: try launching Cursor from Terminal with cursor --disable-extensions, then reproduce the issue. This will tell us if it’s extension-related.

  3. Spindump: if you can catch a freeze, open Activity Monitor, select Cursor Helper (Renderer), then click Sample Process. The text output will be helpful.

One more question: what language are the files in, and does the lag happen only with Agent enabled, or also when you just open the file?

A similar issue is discussed here: IDE performance issues during agent generation. For another user, Process Explorer showed the load was coming from the main process, not extensions.

The team is aware of these performance issues, but the diagnostics will help us understand what’s going on in your specific case.