You can get faster playback by decreasing framerate, obviously because MpegPlayer doesn't have to decode as many frames. I find that 12 fps is the lowest I can get before the video starts to look choppy, but your eyes may differ. 320x180 runs fine at 12fps. I'm not sure if 320x240 at 12fps would still run well, but
this chart seems to indicate so. Note that there was a performance increase at r15341.