Not sure if you found a solution or not, but I noticed the same thing when I first started playing in Ubuntu. I managed to resolve this by doing the following:
System -> Game Configuration -> Input -> Mouse
Slide Head Speed and Head Acceleration all the way to the right.
Click OK/Apply.
I hope that works for you too.
System -> Game Configuration -> Input -> Mouse
Slide Head Speed and Head Acceleration all the way to the right.
Click OK/Apply.
I hope that works for you too.