Anthropic Cowork feature creates 10GB VM bundle on macOS without warning

Hacker News · Mar 2, 2026 · Collected from RSS

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Description After using the cowork feature, Claude Desktop becomes extremely slow - slow startup, UI lag, and slow responses. Performance degrades over time even during a single session. Investigation VM Bundle (10GB) The cowork feature creates a VM bundle at: ~/Library/Application Support/Claude/vm_bundles/claudevm.bundle/rootfs.img This file grows to 10GB and is never cleaned up. It regenerates quickly after deletion (deleted one day, back to 10GB the next). Cleanup Test Results Deleted vm_bundles, Cache, and Code Cache directories (reduced from 11GB to 639MB). Result: ~75% faster immediately after cleanup on tasks that previously failed/hung. Performance Degradation Over Time Even after cleanup (VM bundle at 0 bytes), performance degrades within minutes: Immediately after restart: ~24% CPU at idle After several minutes of use: ~55% CPU (renderer at 24%, main at 21%, GPU at 7%) Swap activity increases (swapins climbing from 20K to 24K+) This suggests a memory leak or accumulating work that causes degradation regardless of VM bundle state. Environment macOS (Darwin 25.2.0) Claude Desktop (latest) 8GB system RAM Observed Behavior High CPU at idle (~24-55% combined across processes) Heavy swap activity that increases over time Performance degrades within minutes of use 10GB VM bundle regenerates after every cowork session Tasks that failed before cleanup now complete (75% faster initially) Workaround Quit Claude Desktop and delete the VM bundle: rm -rf ~/Library/Application\ Support/Claude/vm_bundles rm -rf ~/Library/Application\ Support/Claude/Cache rm -rf ~/Library/Application\ Support/Claude/Code\ Cache Provides ~75% improvement but degrades again over time. Must restart periodically. Expected Behavior Stable CPU usage that doesn't degrade over time VM bundles cleaned up after cowork sessions Usable performance on 8GB RAM systems Filed via Claude Code