[Bug] Severe input lag in plan mode approval prompt with large plan files

Description

When a plan file grows large (50KB+), the approval prompt in plan mode becomes extremely laggy. Selecting options or typing in the text input field has noticeable delay.

Steps to Reproduce

1. Enter plan mode and create/accumulate a large plan file (~50KB or more)
2. Reach the approval prompt:

```

1. Yes, and auto-accept edits
2. Yes, and manually approve edits
3. Type here to tell Claude what to change

```

1. Try to select an option or type in option 3

Expected Behavior

The approval prompt should remain responsive regardless of plan file size.

Actual Behavior

• Significant input lag when selecting options
• Typing in the text field is delayed by several hundred milliseconds per keystroke
• Makes the approval flow frustrating to use

Environment

• OS: macOS
• Claude Code version: latest
• Terminal: iTerm2 / VS Code integrated terminal

Notes

This seems like a rendering issue rather than LLM inference time. The lag occurs during user input, not while waiting for Claude's response. Possibly related to re-rendering large markdown content on each keystroke?