[BUG] Memory leak on Windows caused by GrowthBook feature flags polling — 300-700MB/min on idle

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?

Claude Code leaks 300-700 MB/min on Windows with zero user interaction. Process is completely idle — no prompts entered, just launched.

Memory growth (idle, no input):
04:08:08 -- claude PID:7704 505 MB
04:08:13 -- claude PID:7704 649 MB
04:08:18 -- claude PID:7704 736 MB
04:08:23 -- claude PID:7704 1063 MB
04:08:28 -- claude PID:7704 1351 MB
04:08:33 -- claude PID:7704 1593 MB

4 persistent connections to 160.79.104.10:443 (GrowthBook endpoint) never close.
Setting CLAUDE_CODE_DISABLE_GROWTHBOOK=1 stops the leak immediately.

What Should Happen?

Memory should remain stable on idle (~400-500 MB). GrowthBook polling should not cause unbounded memory growth on Windows.

Error Messages/Logs

Steps to Reproduce

1. Install Claude Code 2.1.71 on Windows
2. Open PowerShell
3. Run: claude
4. Do nothing — just leave it open
5. Monitor memory: Get-Process | Where-Object { $_.Name -match "claude" } | Select-Object @{N="MB";E={[math]::Round($_.WorkingSet64/1MB)}}
6. Observe: memory grows 300-700 MB/min with zero interaction

Workaround: set $env:CLAUDE_CODE_DISABLE_GROWTHBOOK="1" before launching — leak stops immediately.

Network analysis shows 4 persistent connections to 160.79.104.10:443 (GrowthBook endpoint) that never close and accumulate memory buffers.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.71 (Claude Code)

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

PowerShell

Additional Information

Setting CLAUDE_CODE_DISABLE_GROWTHBOOK=1 completely stops the leak.
4 persistent TCP connections to 160.79.104.10:443 observed during idle — never close.
DO_NOT_TRACK=1 and ANTHROPIC_DISABLE_TELEMETRY=1 do not help.
ANTHROPIC_BASE_URL=http://localhost:1 stops the leak (confirms network cause).