https://bugs.winehq.org/show_bug.cgi?id=43893
--- Comment #3 from Alexandre Julliard julliard@winehq.org --- (In reply to Panard from comment #2)
Sure, but in our case, this is to disable only clients in a particular container, not all the clients on the host.
There has to be a way to fix this at the container or Xlib level instead of changing every single app.
Moreover, looking at the current code in winex11.drv/bitblt.c, if the extension is disabled on the server, create_shm_image will still make a lot of work until it gets kicked off by XShmAttach because the current implementation of XShm still enable XShmCreateImage if the extension is disabled ; therefore disabling the extension on the server will lead to very bad performances with wine.
That's work that we do anyway if the extension is available, so the performance will be pretty much unchanged.
The real performance loss will be transferring the bits instead of using shm, but an environment variable won't make any difference there.