Testgl XFree 4.2.0 crash

I am trying to run testgl using RedHat 8.0 (Xfree 4.2.0)
export SDL_VIDEODRIVER=dga
./testgl
switching video resolution X11 crash without messages
using SDL_VIDEODRIVER=x11 work!!!
With Xfree 4.0.3 all work fine.

my video card is Matrox G400

Can anyone explain this, or help me with the speed problem?