Cowork feature creates 10GB VM bundle that severely degrades performance

[mjbyt]

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

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Filed via Claude Code

[bplessis-swi]

Worse part is this VM is running and eating memory even when Cowork is disabled ...

[aeifn]

Why is a virtual machine necessary at all?

[aestwick]

Mine is 21.47GB and counting...

[troy-may]

Just found the same 10GB VM bundle and a cache stuffed with over 15,000 files, no wonder things were getting sluggish with opening the desktop app. Worse it just came back within a single launch and reboot cycle without ever touching Cowork. It’s silently re-provisioning on cold launch and getting bigger 13GB. The rootfs.img.zst being retained alongside the decompressed rootfs.img is wasteful, leaving the compressed source sitting there after it's already been extracted. No cleanup at all. Have to nuke this.

[willn-dev]

I've never used Co-work, yet I still just deleted a 10gb bundle. This is such an obvious memory leak.
Pretty disappointing.

[fadedlamp42]

lol, didn't think I'd be typing rm -r ~/Library/Application Support/Claude today but this was my last straw to fully switch to terminal-based workflows