Claude desktop main process event-loop stall (2+ seconds) during session startup with remote MCP integrations

Description

The Claude desktop main process stalls for 2+ seconds during session warm-up when remote MCP integrations are connected. This causes the UI to be unresponsive at startup and can cause click events (including Recents) to be dropped.

Log Evidence

2026-06-14 17:22:19 [warn] [event-loop-stall] main process blocked for 2269ms (total 1, cumulative 2269ms, rss 256MB)

Earlier in the same session:

2026-06-14 15:07:51 [warn] [event-loop-stall] main process blocked for 1442ms
2026-06-14 15:07:54 [warn] [event-loop-stall] main process blocked for 2360ms
2026-06-14 15:08:01 [warn] [event-loop-stall] main process blocked for 689ms

The stall consistently occurs at the point where remote MCP servers are loaded:

[CCD] LocalSessions.replaceRemoteMcpServers: sessionId=..., serverCount=12

Impact

• UI freezes for 2–4 seconds during session startup
• Clicks on interactive elements (Recents, buttons) during this window are silently dropped
• Makes "Recents not executing" appear as a bug when it is actually a timing/responsiveness issue

Environment

• Claude desktop v1.12603.1.0 (Windows 11 Pro)
• 12 remote MCP integrations connected (Canva, Excalidraw, Figma, Gmail, Google Calendar, Google Drive, Mermaid Chart, Netlify, Notion, Remotion MCP App, Supabase, Vercel)
• Session log: %APPDATA%\Claude\logs\main.log

Suggested Fix

Remote MCP server initialization should be performed off the main thread or deferred until after the UI is interactive, to prevent blocking the Electron main process event loop.