Probably I could try to convert the OpenGL scaling code to GLES or just use some wrapper. Won’t take the decoding work off of the cpu though.
Tried GPWorld and it works fine until you start driving. then it will freeze when you reach a certain speed and play again when it slows down. Looks like the Hardware struggles to decode at faster than original speed.
Will try to get some other game running this evening and rebuild with some more agressive optimisationflags.

Also, if I use resolutions smaller than 1920×1080 the screen will not be in the middle but cut off at the top. But maybe this is just a problem with my setup. Need to get a Pi setup just for developing I think. Using dispmanx-sdl driver to scale up 640×480 to fullscreen in the videohardware could also lead to more performance.

But I’ll check that when I got it more stable.