There is program you can run with a video player to get better performance. It's a third party version of GAPI (game application programming interface). You can find it here:
http://www.wincesoft.de/html/gapi_for_hpc_s.html
I've usually seen an improvement of around 20%.
I know this post is quite far outside the usual topics here on MobileRead, but since it might be useful to someone I'll post it anyway.