Severe Chrome lag and unclickable UI when using serverReadyAction in Cursor

Bug Reports
1

Bug Description:
When using serverReadyAction to launch Chrome via a debug configuration in Cursor for a Next.js app, the resulting Chrome window becomes extremely laggy. The app loads, but UI elements are unclickable or behave inconsistently, and overall page performance drops significantly. Cursor itself also becomes sluggish.

Steps to Reproduce:

Use the following launch.json configuration:

json

{
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Dev Server with Chrome",
      "type": "node-terminal",
      "request": "launch",
      "command": "npm run dev",
      "serverReadyAction": {
        "action": "startDebugging",
        "pattern": "http://localhost:3000",
        "name": "Launch Chrome Browser"
      }
    },
    {
      "name": "Launch Chrome Browser",
      "type": "chrome",
      "request": "launch",
      "url": "http://localhost:3000",
      "webRoot": "${workspaceFolder}"
    }
  ]
}

Steps:

  1. Run the “Dev Server with Chrome” config.
  2. Wait for http://localhost:3000 to appear in the terminal.
  3. Cursor launches Chrome and starts debugging.
  4. Observe:
  • App becomes extremely slow
  • Elements are unclickable or glitchy
  • Open the dev console and see that it constantly gets stuck pausing and unpausing the debugger

Environment Details:
Framework: Next.js 13.5.10
OS: macOS 15.4 (24E248)
Cursor Version: 0.48.7 (Universal)

Blocking:
Yes — this completely breaks the Chrome + debugger experience in Cursor.
It works perfectly in VS Code using the exact same launch.json.
Since Chrome launch flags can’t be overridden in Cursor, this can’t be worked around.

2

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