Xfwm4 won't unredirect fullscreen windows when SDL 1.3 or 2.0 are used. This was tested with Trine 2 which use SDL 1.3 and Torchlight which use 2.0. Performance are worse normal and there's tearing even with vsync. When disabling compositor performance and vsync go back to normal. SDL 1.2 applications are properly dealt with Xfwm4, so performance and tearing issues are nonexistent.
Can you provide a simple C reproducer? I don't play games...
This commit here: http://lists.libsdl.org/pipermail/commits-libsdl.org/2011-February/012224.html Shows that SDL no longer use override redirect windows but regular windows for fullscreen. Unredirection of fullscreen windows is only for override redirect. We cannot unredirect _regular_ windows when fullscreen, that would break all compositing with normal windows when fullscreen. There is no way to fix this.
*** Bug 10051 has been marked as a duplicate of this bug. ***