[BUG] Claude Code super slow after "A to show all projects" update in "Resume Session"

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

After the update, a few weeks from now, whoever had both huge sessions or multiple sessions inside ~/.claude/ folder and its subfolders are having serious issues regarding speed and huge resource consumption as you can see from my screenshot:

<img width="953" height="722" alt="Image" src="https://github.com/user-attachments/assets/46b061a0-0268-4ec1-a7a8-a25caa367e87" />

The issue is amplified when using the SDK on a folder used by Claude Code as the massive load o data from the SDK agents also get picked up by Claude Code, making Claude Code take 10 minutes for an answer, while it stays completely frozen.

What Should Happen?

Big files and multiple sessions should not be fetched nor indexed until and unless needed by the user in a precise moment. There's no need to go through all the old sessions each time claude code is opened or is running.

Since the update I had to clear ~/.claude/ already two times. I'm on heavy agentic use and while we are a minority on such a high volume, we're still the ones that use the most your products, SDKs and APIs, and I hope our ability to use Claude Code and the SDK goes back to normal. Having to choose between an older working version with missing features and a new version that becomes unusable after a couple 100 sessions has become very painful.

Error Messages/Logs

Steps to Reproduce

1. Get to 1000+ sessions
2. Open Claude Code
3. Query Claude
4. Hope for an answer in 10+ minutes

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Not sure, I'd say a month ago was working fine

Claude Code Version

2.1.7

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_