[BUG] Severe input stuttering/jumping when typing fast in TUI - characters appear in bursts

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?

Description

When typing quickly in the Claude Code TUI prompt, characters appear in stuttering bursts instead of smoothly. The cursor "jumps" and characters are delayed, making fast typing extremely frustrating. This happens even in a fresh session with minimal context.

Video Demonstration

https://github.com/user-attachments/assets/cdd77dbd-2fbc-43be-aae4-49876c66bd95

Actual Behavior

Characters appear in stuttering bursts with visible delay. The faster you type, the more pronounced the "jumping" effect becomes.

What Should Happen?

Characters should appear immediately and smoothly as typed, similar to normal terminal input.

Error Messages/Logs

Steps to Reproduce

1. Open Claude Code in any terminal (tested: Kitty, GNOME Terminal, Alacritty)
2. Start typing rapidly (e.g., "gggggggggggggggg" or any fast text)
3. Observe the characters appearing in delayed bursts instead of smoothly

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.12

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

Environment

• Claude Code version: 2.1.12
• OS: Ubuntu 24.04.3 LTS
• Kernel: 6.12.57-cachyos-lts-znver4
• Desktop: GNOME 46 (Wayland)
• Terminals tested: Kitty, GNOME Terminal, Alacritty - all exhibit the same behavior
• Hardware: AMD Ryzen 9 9950X3D, 128GB RAM, NVMe SSD
• Node.js: v25.2.1

## Notes

• Typing in the terminal itself (outside Claude Code) is perfectly smooth
• The issue occurs immediately on a fresh session, not just after long conversations
• Disabling telemetry (DISABLE_TELEMETRY=1) does not fix the issue
• This appears to be related to React Ink's TextInput component re-rendering on every keystroke

## Related Issues

• #3045 - IME issues investigation (same root cause: React Ink)
• #7430 - High keystroke latency
• #1913 - Terminal flickering (related TUI performance issues)