Well, as the topic says after 3-4 jumps it slows down alot, to the point I have to log off and log back in again

Well, no resolution yet, downloaded the latest driver (on a pleasant not ATI finally added OpenGL 2.0 support), but the issue stands.

Try turning down the texture resolution in the Video options.
What video card do you have (besides just ATI)?

Same problem here. Nice and fast and smooth to begin with, but after a few jumps it becomes unplayable. Have to re-login to fix it. AMD Sempron 3000 laptop, ATI X700 graphics card, Gentoo Linux.

This seems to be resolved for me now. Whether this is down to turning down the texture res or the new client, I'm not sure. Will test with the texture res turned back up shortly...

Cheers