[Wine] Wine lags!

[xaber1488]

Hi guys! I have a little problem! I installed ubuntu 9.10 and so reinstalled wine (version 1.0.1). I also installed playonlinux and, via playonlinux, I installed call of duty 2 and guild wars (platinum rated games, if I'm correct): they work directly out of the box!
But I have 2 problems: the major one is that every 5-10 seconds, my gameplay lags for 1-2 seconds, that is really annoying! The second one is that sometimes the sound doesn't start at the game startup!
These 2 problems are common to both games!
What could the problem be?
I have an ati mobility radeon HD 2600 and didn't modify significant options, nor added any win library!
Thanks in advance!