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When using Windsurf in WSL (via Remote - WSL), the editor may become slow, unresponsive, or repeatedly disconnect from the WSL backend. This is most commonly caused by extensions performing aggressive file watching and indexing over the WSL filesystem, which saturates the Plan 9 (9P) protocol—the filesystem bridge between Windows and the WSL Linux environment. This is more likely in large repositories and when multiple language servers run concurrently.

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Symptoms

  • Windsurf is noticeably slow or laggy when connected to WSL
  • The editor frequently disconnects from the WSL backend and attempts to reconnect
  • Disconnections occur during active development (e.g., while using Cascade) and while the editor is idle
  • Windsurf crashes or becomes unresponsive, requiring a restart of both the IDE and WSL (wsl --shutdown)
  • WSL memory usage grows over time, even on systems with 32 GB+ of RAM
  • WSL diagnostic logs show large numbers of P9 Reply_Rlerror events (file-not-found errors)
  • Performance is normal when using Windsurf outside of WSL (e.g., opening a local Windows folder)
  • Common workarounds (restarting WSL, reinstalling Windsurf, increasing .wslconfig memory) do not resolve the issue on their own

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Root Cause

Communication between Windows and the WSL Linux filesystem uses the Plan 9 (9P) protocol, which has limited throughput compared to native filesystem access. When extensions are installed in the WSL environment, some perform aggressive file watching and indexing across the entire workspace. In large repositories (e.g., 250,000+ files, 5+ GB), this generates a massive volume of filesystem operations over the 9P bridge, which can:
  • Saturate the protocol’s capacity
  • Produce thousands of file-not-found errors (Reply_Rlerror)
  • Cause the connection between Windsurf and the WSL backend to drop
  • Contribute to growing memory pressure inside WSL over time
This is compounded when multiple language servers are also running (e.g., Sorbet, Ruby LSP, TypeScript, etc.), since they add additional file-watching overhead. The combined filesystem activity from extensions and language servers can overwhelm the 9P bridge even on systems with 32 GB+ of RAM. A known example is the Vue (Volar) extension, which has been observed to cause excessive file indexing in WSL environments even when the workspace does not contain Vue files. This issue is documented in the VS Code ecosystem: microsoft/vscode-remote-release#11091 This is especially likely if you have carried over a large set of extensions from VS Code or another editor that are not needed for your current project.

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Solutions

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1. Clean reinstall of the Windsurf server in WSL

Delete the Windsurf server directory inside WSL and let Windsurf reinstall it on next connection: 
rm -rf ~/.windsurf-server
Then reconnect Windsurf to WSL. The server will be reinstalled automatically.

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2. Minimize installed extensions (highest impact)

Only install extensions you actively need for the repository you are working in.
  • Open the Extensions panel in Windsurf while connected to WSL
  • Review which extensions are installed in the WSL environment (not just locally)
  • Disable or uninstall extensions you do not need—especially those that perform heavy file watching or indexing
Known problematic extensions in WSL:
  • Vue (Volar) — confirmed to cause excessive file indexing over the 9P bridge, even in non-Vue projects. Uninstalling this extension alone has resolved disconnections for multiple users.
  • Other framework-specific language extensions (Angular, Svelte, etc.) may behave similarly if installed but not needed for the current workspace.
Do not assume that extensions which work fine on a local (non-WSL) setup will behave the same in WSL. The 9P filesystem bridge is the bottleneck—extensions that are harmless locally can become destabilizing when every file operation must cross the protocol boundary. Reducing extension-driven filesystem activity directly reduces load on the 9P bridge.

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3. Optimize WSL resource limits

Create or edit the file %USERPROFILE%\.wslconfig on your Windows host (e.g., C:\Users\<YourUser>\.wslconfig) with resource limits appropriate for your system: 
[wsl2]
memory=16GB
swap=4GB
processors=4
autoMemoryReclaim=gradual
Adjust values based on your system’s available resources. After saving the file, restart WSL: 
wsl --shutdown
Then reopen Windsurf and reconnect to WSL.

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Diagnosis

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Check WSL diagnostic logs for 9P errors

To confirm that 9P saturation is the cause, collect WSL diagnostic logs: 
wsl --debug-shell
Or collect a full diagnostic bundle: 
Invoke-WebRequest -UseBasicParsing "https://aka.ms/wsldiag" -OutFile wsldiag.ps1
.\wsldiag.ps1
Look for high volumes of Reply_Rlerror events in the 9P/filesystem logs. Thousands (or more) typically indicate that extensions or processes inside WSL are generating excessive filesystem requests that the 9P bridge cannot keep up with.

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When to use which fix

  • Minimize extensions if you have many extensions installed in WSL that you don’t actively need, or if you migrated extensions from another editor. (Highest-impact change.)
  • Clean server reinstall if the Windsurf server state may be corrupted or stale (e.g., after a failed update or previous crash).
  • Optimize .wslconfig if WSL is consuming excessive host resources, or if you have not previously configured resource limits. (General WSL stability improvement.)
For best results, apply all three. The combination of a clean server, minimal extensions, and tuned resource limits addresses both the root cause (9P saturation from extension activity) and contributing factors (resource exhaustion).