[BUG] VS Code UI becomes sluggish when running Claude Code orchestrator with many sub-agents (likely terminal render bottleneck)

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 I use a prompt within Claude Code to act as an orchestrator (itself prompting Claude Code to launch multiple agents in parallel), the VS Code UI gets sluggish, especially the Integrated Terminal. The heavy compute runs remotely, but local responsiveness degrades as agent logs stream rapidly (spinners, carriage returns, token-by-token output). This looks like a terminal rendering/reflow bottleneck, not model compute.

Environment

Device: MacBook Air

macOS: 14.7.8

What Should Happen?

Expected Behavior

VS Code remains responsive while multiple agents stream logs.

Actual Behavior

VS Code becomes noticeably sluggish during high-frequency terminal output, despite compute being remote.

Notes / Clues

Severity scales with number of agents and write frequency (carriage-return updates, token streams, ANSI).

Error Messages/Logs

None

Steps to Reproduce

In VS Code, open Claude Code.

Use a prompt that instructs Claude Code to act as an orchestrator, launching N sub-agents in parallel (roles from .md files).

Observe the terminal streaming frequent progress/spinner/token updates from multiple agents.

VS Code UI (and terminal) becomes laggy: slow scrolling/echo, delayed input, occasional brief freezes.

Claude Model

Sonnet (default)

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

1.0.123

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Suggestion: an option to batch/limit terminal writes and/or coalesce carriage-return updates when running inside the Integrated Terminal.