[BUG] extremely slow paste-in (e.g. console log segment) especially with a lot of session history

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?

When reporting, please include:

1. Title: "Severe paste performance degradation with large session

history"

1. Details:

• Paste operations take 5-10 minutes with accumulated session history
• Screen redraws and history flashing occurs during paste
• Most pronounced when pasting large text blocks (console logs)
• Issue worsens with multiple continued sessions

1. Environment:

• Platform: macOS (Darwin 24.6.0)
• Claude Code version
• Session continuation count if known

Workaround for now: Start fresh sessions more frequently when dealing
with large paste operations (which you're doing now).

What Should Happen?

prompt paste

Error Messages/Logs

Steps to Reproduce

paste a large block of text into claude code, especially with substantial session history accumulated

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.0.42 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_