X11 Forwarding by DevContainers significantly drops FPS.

[nidnesandne]

• VSCode Version: 1.78.2
• Local OS Version: Windows 10
• Local chip architecture: x64
• Reproduces in: Remote - Containers

Steps to Reproduce:

1. When running glxgears within WSL, its FPS is as follows.

6303 frames in 5.0 seconds = 1260.489 FPS

OK.

2. When I manually create a Docker container on WSL and do X11 Forwarding by myself with -v /tmp/.X11-unix:/tmp/.X11-unix mount option, the FPS is as follows.

6105 frames in 5.0 seconds = 1220.828 FPS

Good. It is down a bit, but fast enough.

3. However, if I execute glxgears in the DevContainer with X11 Forwarding by the function of DevContainers, the FPS is as follows.

812 frames in 5.0 seconds = 162.287 FPS

Hmmm...

According to the Dev Containers logs, it seems that it's Forwarding with a different approach than the mount. This may be Dev Containers' philosophy, but why so slow?

DevContainers does not seem to provide a way to disable the X11 Forwarding feature, so I am doing the following hack to keep a high FPS even with DevContainers.

[devcontainer.json]
{
    ...
    "mounts": [
        {
            "source": "/tmp/.X11-unix",
            "target": "/tmp/.X11-unix",
            "type": "bind"
        }
    ],
    "containerEnv": {
      "DISPLAY": ":0"
    }

In this way, an error occurs when creating a container, but the container itself is created and Forwarding is performed by bind mount, so the FPS does not drop.

[2772 ms] Start: Run in container: test -e /tmp/.X11-unix/X0
...
[2774 ms] Start: Run in container: test -e /tmp/.X11-unix/X1
...
[2776 ms] Start: Run in container: mkdir -p '/tmp/.X11-unix'
...
[2779 ms] X11 forwarding: DISPLAY in container (:1) forwarded to wsl host (:0).
...
[3115 ms] Container server: Error: listen EROFS: read-only file system /tmp/.X11-unix/X1
    at Server.setupListenHandle [as _listen2] (node:net:1415:21)
    at listenInCluster (node:net:1480:12)
    at Server.listen (node:net:1579:5)
    at /tmp/vscode-remote-containers-server-f104bdef-0c3d-4eda-94cc-b27ecd1a84c3.js:12:10714
    at new Promise (<anonymous>)
    at /tmp/vscode-remote-containers-server-f104bdef-0c3d-4eda-94cc-b27ecd1a84c3.js:12:10697
    at async Promise.all (index 1)

At least, I would like to be provided a way to disable X11 Forwarding.