Slow start- It takes long time to open files and folders

Support Bug Reports
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1

Where does the bug appear (feature/product)?

Somewhere else…

Describe the Bug

Hi, It takes long time to open files and folders now. It has gotten worse over the last month. I write code in ipynb, and I know that the files can heavy. Could that be why?

Steps to Reproduce

Try to open a folder with data and scripts in ipynb files

Expected Behavior

The files should load in a few seconds.

Operating System

Windows 10/11

Version Information

Version: 3.4.17 (system setup)
VSCode Version: 1.105.1
Commit: 93e603f703cd553a6bb3644711a3379bbbb31180
Date: 2026-05-13T21:39:55.724Z
Layout: editor
Build Type: Stable
Release Track: Default
Electron: 39.8.1
Chromium: 142.0.7444.265
Node.js: 22.22.1
V8: 14.2.231.22-electron.0
OS: Windows_NT x64 10.0.17763

Does this stop you from using Cursor

No - Cursor works, but with this issue

5

Hey, performance issues with Jupyter notebooks .ipynb on Windows are a known thing, and there are a few similar reports, like this thread Jupyter Notebook rendering takes forever eternity asgard time and this one Cursor SO slow the last two weeks. We’re tracking the issue, but I can’t share a specific ETA for a fix yet.

A couple things that can help narrow down what’s happening on your side:

  • Start Cursor with extensions disabled and see if it makes a difference:

    cursor --disable-extensions

    This often helps confirm if an extension is causing the slowdown, like Jupyter or Python.

  • Open Process Explorer Cmd+Shift+P then Developer: Open Process Explorer while opening an .ipynb and check which process is using CPU or memory, like extensionHost, ptyHost, or the renderer.

  • Your Windows 10 version is build 17763, which is LTSC 2019 from 2018. Newer Electron apps can run slower on builds like that. If you can update Windows, it’s worth trying since it can help performance a lot.

If you find one process or a specific extension that clearly triggers the slowdown, send it here and it’ll help the investigation.

7

The issue is Cursor specific, because other IDEs do not face the same issues with the same repos.

One quick fix I use is to first open the folder in Cursor, and close all open windows that have .ipynb or markdown files(while it’s all still loading) and close the Cursor window. Then reopen the folder in Cursor, and it loads up quickly.

9

Thanks for the response. It’s nice to know that it is a known thing. I’ll try different walkarounds as suggested.:sun:

10

Thanks for getting back to us. Another workaround from @Adarsh_Pandey in the post above is worth trying: open the folder, close all .ipynb and markdown tabs while everything is loading, then restart Cursor and open the folder again. A few users have already said this helps.

If you find a specific extension or a process in Process Explorer that clearly slows things down when opening .ipynb, drop it here and we’ll add it to the investigation.

11

Hi, Your solution has also worked for me now; open new folder, close the notebooks and markdowns that are automatically opened, close cursor, open cursor and the folder again. :slight_smile:

13

Hey @Lars_Kjaer, glad to hear the workaround helped. We’re still working on overall Jupyter Notebook performance, so if you run into slowdowns again in a future version, please open a new thread and we’ll take another look.