Desktop Commander MCP: Performance degradation due to infinite React render loop in skills system #4895

Problem Summary

Claude Desktop becomes unusable after 4-5 messages in a conversation due to severe UI lag (1-2 second input delay, scroll stuttering). Multiple users report this issue started around July 30, 2025.

Technical Root Cause

Infinite React render loop triggered by failing API call to skills system:

GET /mnt/skills/all_skills.json → 404 Not Found
→ useEffect() triggers retry → component re-renders → new GET → still 404
→ loop repeats endlessly (1000+ times per session)

Impact

• Input lag: 500-2000ms delay before letters appear
• UI performance: Scroll and interaction stutter
• Memory growth: Constant heap inflation
• Cross-platform: Affects both Claude Desktop (Electron) and Claude Web (Chrome/Firefox)

User Reports

User 1:

• System: Windows 11 Pro 24H2, 12-core CPU, 64GB RAM, NVMe SSD
• System usage: <10% during lag
• Claude Desktop version: v0.12.55 (d55c63) - build 2025-07-25T17:43:32.000Z
• Key finding: Same lag occurs in Claude Web when opening identical chats

User 2:

• Confirms identical behavior starting yesterday
• Conversations become "basically unusable" after certain length

Technical Analysis

Error patterns observed:

• Sentry flood (429 Too Many Requests)
• Auth warnings (FedCM get() rejects, Cross-Origin-Opener-Policy issues)
• Repeated stack traces:

ux @ ...js:1
uS @ ...js:1

Cross-platform consistency:
Claude Desktop shows identical behavior to Chrome because both use Chromium engine, confirming this is a frontend issue, not local system problem.

Recommended Fix

Immediate:

• Temporarily disable skills system until proper error handling implemented

Long-term:

• Add retry limit or circuit breaker in useEffect for skills API calls
• Implement graceful failure instead of re-render looping
• Add proper error boundaries around skills components

Environment

• OS: Windows 11 Pro 24H2
• Claude Desktop: v0.12.55 (d55c63)
• Browser: Chrome v138.0.7204.183, Firefox (same behavior)
• Timeline: Issue started around July 30, 2025 (coinciding with Claude.ai incident)

Reproduction Steps

1. Start new conversation in Claude Desktop or Web
2. Exchange 4-5 messages
3. Observe increasing input lag and UI stuttering
4. Check browser dev tools for repeated 404 errors on skills endpoint

This appears to be a critical performance regression affecting multiple users across platforms.