[BUG] Fullscreen rendering mode: scrolling is laggy/stuttering in VSCode integrated terminal on Windows

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 using Claude Code in fullscreen rendering mode inside VSCode's integrated terminal, scrolling through conversation output is noticeably laggy — frames are dropped and the viewport frequently freezes for a moment before catching up. The issue does not occur in native Windows Terminal.

What Should Happen?

Smooth, responsive scrolling through the conversation history, consistent with native terminal behavior.

Error Messages/Logs

Steps to Reproduce

1. Open VSCode integrated terminal
2. Set CLAUDE_CODE_NO_FLICKER=1
3. Launch claude
4. Have a long conversation that produces several screens of output
5. Scroll up/down using mouse wheel or touchpad

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.119

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

VS Code integrated terminal

Additional Information

_No response_