UI is very laggy when you have a lot of long local agent chats open

Support Bug Reports
1

Describe the Bug

With the new “Agents” panel on the left open, and 20+ very long chats, the Cursor UI becomes painfully unresponsive. Like clicking “New agent” takes 5+ seconds.

I think it’s worse when one or more agents are actually doing stuff.

This is on a brand new Mac Studio M4 Max with 128GB of RAM :frowning:

Steps to Reproduce

Use the left Agents bar to create a whole bunch of local agents, and have long conversations with them to make large numbers of code changes. Then click “New Agent” or try typing in a terminal window.

Expected Behavior

On ~the fastest computer that money can buy, with few other apps open, Cursor should not be slow.

Operating System

MacOS

Current Cursor Version (Menu → About Cursor → Copy)

Version: 1.4.2 (Universal)
VSCode Version: 1.99.3
Commit: 07aa3b4519da4feab4761c58da3eeedd253a1670
Date: 2025-08-06T19:23:39.081Z (1 day ago)
Electron: 34.5.1
Chromium: 132.0.6834.210
Node.js: 20.19.0
V8: 13.2.152.41-electron.0
OS: Darwin arm64 24.6.0

Does this stop you from using Cursor

Sometimes - I can sometimes use Cursor

1 Like
2

I think the UI thread is being blocked by terminal operations that the chat windows are running.

3

I’m also experiencing the same issue, and it’s making Cursor extremely hard to use.

With many long local agent chats open, even simple actions like clicking “New Chat” or typing in the terminal lag by several seconds.
This happens consistently, and the slowdown feels severe enough to disrupt normal work.

I really hope this can be addressed soon.
it’s currently a major productivity blocker.

For reference, my system specs are:
CPU: Intel Core i9-14900KF
RAM: 128GB DDR4 3200MHz
Storage: NVMe SSD 2TB (60% used)

3 Likes
4

Man this lagging UI is driving me crazy.

5

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