Anthropic's Cowork Feature Creates 10GB VM Bundle on macOS, Causing Severe Performance Issues
Key Takeaways
- ▸Anthropic's Cowork feature creates a 10GB VM bundle on macOS that is never automatically cleaned up, causing severe performance degradation
- ▸Performance issues include slow startup, UI lag, high CPU usage (24-55%), and increasing swap activity that worsens over time
- ▸Manual deletion of the VM bundle provides 75% performance improvement, but the file regenerates and degradation returns within minutes
Summary
Users of Anthropic's Claude Desktop application are reporting severe performance degradation caused by the Cowork feature, which creates a 10GB virtual machine bundle that is never automatically cleaned up. According to a GitHub issue filed by user mjbyt, the VM bundle is stored at ~/Library/Application Support/Claude/vm_bundles/claudevm.bundle/rootfs.img and grows to 10GB without user notification or consent. The file regenerates quickly even after manual deletion, causing Claude Desktop to experience slow startup times, UI lag, and sluggish responses.
The performance issues appear to be twofold. First, the 10GB VM bundle itself consumes significant disk space and system resources. When users manually delete the vm_bundles, Cache, and Code Cache directories (reducing total size from 11GB to 639MB), they report approximately 75% faster performance on tasks that previously failed or hung. However, this improvement is only temporary.
More concerning is the progressive performance degradation that occurs even after cleanup. Users report that CPU usage climbs from 24% immediately after restart to 55% within minutes of use, with the renderer process consuming 24%, the main process 21%, and GPU 7%. Swap activity also increases significantly, with swapins climbing from 20K to 24K+, suggesting a potential memory leak or accumulating workload issue. The problem is particularly acute on systems with 8GB of RAM, where the application's resource consumption can severely impact overall system performance.
As a temporary workaround, users must periodically quit Claude Desktop and manually delete the VM bundle and cache directories using terminal commands. While this provides immediate relief with approximately 75% performance improvement, the degradation returns within minutes to hours of continued use, requiring frequent restarts. The issue has been labeled as high-priority and a bug on Anthropic's GitHub repository, but no official fix or timeline has been announced.
- The issue appears to involve both the large VM bundle and a separate memory leak or resource accumulation problem
- Users on 8GB RAM systems are particularly affected, with no official fix currently available from Anthropic
