[BUG] Input buffer becomes unusable with large prompts

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?

I'm experiencing a severe performance degradation that makes Claude Code unusable for my workflow.

Issue: When typing longer prompts (pasting logs, multi-line code, etc.), every keystroke causes the input buffer to scroll to the top and back to the bottom. Performance degrades exponentially with buffer size - eventually reaching seconds per keystroke, making the tool completely unusable.

This appears related to the unresolved "high speed scrolling" issue that's been open for months. The fact that this occurs across all terminal environments suggests it's a fundamental architectural problem rather than environment-specific.

Business Impact: This bug has forced me to abandon Claude Code entirely. I'm switching to Codex, which means you're losing ~$500-600/month in API usage from my account alone. I suspect I'm not the only user hitting this wall.

Request: Either prioritize fixing this core usability issue or acknowledge if it's not feasible to resolve, so users can make informed decisions about tooling investments. Maybe build an app where you have control.

This has been an otherwise excellent product, but this performance issue is becoming a showstopper for any serious development work.

What Should Happen?

The input buffer should not cause the user to suffer through high speed scrolling with every keystroke.

Error Messages/Logs

Steps to Reproduce

1. Type a lot of text into the input buffer

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

1.0.107 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

iTerm2

Additional Information

_No response_