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\ CacheProvides ~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