Laggy playback

[Shaoiken]

Hey Guys,

I recently switched to SMPlayer and use the MPlayer Version from here: http://kovensky.project357.com/ (the site can be reached via google cache only at the moment. It runs great for the most stuff, but with the 1080p wmvs and qts from http://guildwars2.com/en/media/videos/ I enjoy a nice dia show.
I turned off the loop filter, which didnt help (guess because it's for h.264 only) and increased the threads to 4 at a time, as I have a quadcore prozessor.

Any ideas how to fix this? Also, does SMPlayer or any MPlayer versions have cuda support?