Claude Desktop bug: 1.8 GB Hyper-V VM launches on every start, even for chat

A GitHub issue filed against Anthropic’s Claude Desktop app for Windows reports that the application spawns a full Hyper-V virtual machine consuming roughly 1.8 GB of RAM on every launch — regardless of whether the user intends to use the Cowork/agent features that actually require it. Once a user has run Cowork at least once, simply reopening the app (or rebooting) triggers the Hyper-V Host Compute Service via an RPC event, spawning a vmwp.exe process that shows up as ‘Vmmem’ in Task Manager. On the reporter’s 16 GB laptop, that means over 11% of total memory is consumed by idle infrastructure before any real work begins.

The reporter’s diagnostics rule out the usual suspects: WSL, Docker, Hyper-V management tools, and Windows Sandbox are all absent or disabled, with VirtualMachinePlatform the only enabled virtualization feature. They also found 2,689 stale session files in the app’s local-agent-mode-sessions directory that were never cleaned up, and Hyper-V event logs filled with recurring ‘invalid JSON document’ errors. Deleting the session files and killing the VM processes doesn’t help — relaunching the app immediately respawns the VM. The only durable workaround is disabling VirtualMachinePlatform entirely, which breaks Cowork, or manually killing vmwp and vmcompute after every launch.

The report asks for three fixes: lazy initialization so VM infrastructure only starts when an agent session is actually requested, automatic cleanup of old session data, and graceful fallback to chat-only mode when VM startup fails or isn’t needed. The issue highlights a broader tension as AI desktop apps bundle sandboxing and virtualization layers for agentic features — resource costs that land on all users, including those who never touch agent mode.