[BUG] Desktop 2.42304.0 freezes ~3s after launch on Code tab: renderer pegged at 100% CPU; moving claude-code-sessions aside fixes it

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?

[BUG] Desktop 2.42304.0 freezes ~3s after launch on Code tab: renderer pegged at 100% CPU; moving claude-code-sessions aside fixes it

Environment: Claude Desktop 2.42304.0 (bundled Claude Code 2.1.299), macOS 15.7.3, MacBook Air M1, 8 GB RAM

What happens: Since the auto-update to 2.42304.0, the app freezes ~3s after every launch. One "Claude Helper (Renderer)" process sits at ~100% CPU (one core); the main process is idle (~2%). Force-quit and relaunch don't help.

Logs:

• main.log shows a normal startup with no errors and keeps writing after the freeze. Startup lands on the Code tab (sidebar_mode: 'code', landing: 'code'), with 548 known session ids and 228 deferred archived sessions loaded (2650 ms).
• claude.ai-web.log stops writing at launch, with no error. On every launch since the update it shows "MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 ...LocalSessions_onEvent listeners added" (also ...AppPreferences_preferencesChanged).

Workaround: Moving ~/Library/Application Support/Claude/claude-code-sessions aside makes the app launch and work normally.

Last working version: the build before 2.42304.0.

What Should Happen?

Claude Desktop should launch, show its window and stay responsive, including when it opens on the Code tab with a large list of past sessions.

Error Messages/Logs

Steps to Reproduce

1. Have about 550 Code sessions in claude-code-sessions, with the app last left on the Code tab
2. Update to 2.42304.0
3. Launch Claude Desktop: the UI freezes about 3s in, with the renderer at 100% CPU
4. Quit, move claude-code-sessions aside, relaunch: the app works normally

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

the build before 2.42304.0 (I think 2.37337.1)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_