Autocomplete slow with large files
Rider 2024.3.9 - Unity project.
The problem:
- When I start typing a method name, it often takes about half a second for suggestions to appear.
- Upon accepting a suggestion, the method name text is added instantly, but it takes another half second for the parenthesis to be generated and for the cursor to be moved inside them.
What I've tried:
- Disabled solution wide analysis.
- Disabled Rosalyn analyzers.
- Disabled all 3rd party plugins.
- Disabled Unity plugin + closed Unity.
- Tried many 2025 and 2026 versions, including 2026.2.3.1 where this was supposedly fixed. The problem is even worse in all of them; even with AI code completion off.
Additional Info:
- This issue scales with file size. With a small <200 line CS file the delay is negligible. When files get over 1000 lines it starts to become a major impediment to productivity.
- Ryzen 5600X.
- CPU usage stays below 70%.
- Memory usage stays below 50%.
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Hello!
Thank you for the detailed list of everything you already tried. Sorry to hear that completion slows you down this much in large files.
This looks like a known issue: RIDER-138097 Code completion & scroll stutter. In that issue, the completion list appears late, and the parentheses show up about a second after a completion item is accepted, the same as you describe.
Unfortunately, it is not fixed yet. When the developers schedule the fix, the issue will show the version. Please vote for the issue and follow it to be notified about updates: Watching YouTrack issues.
Your report adds a detail that the issue does not have yet: the delay grows with the file size. To help the developers check your case, could you please collect the following in 2026.2.3.1?
Please upload the files to https://uploads.jetbrains.com and share the Upload ID that the page shows after the upload. The upload is private, so it is safe to post the ID here: only JetBrains can open the files.
2026_10_26_GuDC5KbF1Ah159vHU9rPvH
Hello!
Thank you for the backend snapshot and the logs from 2026.2.3.1, and for adding the detail about the number of classes per file to the issue.
Could you please record a timeline snapshot in the same file?
1) Select Help | Diagnostic tools | Profile Backend with Timeline.
2) Accept several completion items in that file over about 20 seconds.
3) Select Help | Diagnostic tools | Backend: stop profiling.
4) Upload the snapshot to https://uploads.jetbrains.com and share the Upload ID here or in the YT issue.
The full steps are in SUPPORT-A-3807 Rider is slow or CPU usage is high. Backend performance snapshot.
As to your first snapshot, the editor waits for the background code analysis of the file before it inserts the text: 2.2 seconds in total when accepting completion items and 1.7 seconds when typing. The timeline snapshot will show which part of the analysis keeps the editor waiting. I've added this analysis to the issue for our developers: RIDER-138097 Code completion & scroll stutter.
Thank you in advance and have a great day!
Thank you for confirming the issue. Here is the timeline: 2026_10_29_5HVWcxfTy1Zt4jcMLRpeF3
Hi Sy!
Thank you for the timeline. I've added it to the mentioned RIDER-138097. I don't have any updates or workarounds for now. Please follow the issue to be notified when there is an update.
Thanks!