[BUG] High CPU/memory usage - regression in recent versions

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

Claude Code is consuming significantly more CPU and memory than it did previously. The high resource usage persists even with normal usage patterns and wasn't an issue in earlier versions.

Environment

• Claude Code version: 2.1.27
• OS: macOS 15.7.1 (Sequoia)
• Hardware: MacBook Pro, Apple M3 Pro, 18GB RAM

Configuration

• 2 MCP servers (Figma, Puppeteer)
• 5 plugins enabled (code-simplifier, scientific-skills, session-wrap, clarify, agent-council)
• Custom env settings: ENABLE_TOOL_SEARCH=1, MAX_THINKING_TOKENS=31999

Observed behavior

• CPU usage rises to near 100%
• Memory usage exceeds 1GB
• This wasn't happening in previous versions with similar context window usage
• Resource usage seems disproportionate even when context is near 100%

What Should Happen?

Resource usage should remain reasonable regardless of context window size, as it did in earlier versions.

Error Messages/Logs

Steps to Reproduce

1. Start Claude Code in a project directory
2. Have MCP servers configured (Figma, Puppeteer) and plugins enabled
3. Use Claude Code normally for an extended session:

• Read/edit multiple files
• Use Task tool to spawn subagents
• Let context window fill up (50%+)

1. Monitor Activity Monitor - observe CPU climbing toward 100% and memory exceeding 1GB
2. Issue persists even after running /compact to reduce context

Note: This was not an issue in earlier versions with the same configuration and similar usage patterns. The high resource usage appears to be a regression.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.27

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_