This is something for the Mac users out there: When you play Cube2/Sauerbraten on OS X you are handicapped compared to others (= linux and windoze users)! The problem is called "mouse acceleration" and it's turned on in OSX and different from win and linux, there is no setting in OS X to change that...
What mouse acceleration does is it moves you mouse arrow on the screen further the faster you physically move your mouse on your desk. As an example with imaginary values: you move your mouse for exactly 4 inches in 1 second, then the mouse arrow on the screen moves 200 pixels. If you move the mouse the same 4 inches in half a second it moves 400 pixels on your screen. And if you move the mouse the 4 inches in a quater of a second the distance will be 800 pixels on the screen.
What's bad about this is that your body can only guess (approximately) how far a movement in a certain amount of time moves the mouse on the screen, but it's just a "feeling" and no matter how good you will get at it, it stays half as good as it could be if there was no accelleration.
Without acceleration, your mouse pointer on the screen moves in a set ratio. E.g.: if you move the mouse one inch it moves 200pixels on the screen, no matter how fast you perform the movement. This is way more natural, as your body is used to this in real life. If you run a yard, it will always be a yard that you have to run, no matter how fast you do it. ;-)
It will take you a while to get used to it, but in my case it raised the usual accuracy rate in insta modes significantly once I got used to it.
So why don't you give it a try?
Ok, now, this is how to turn mouse acceleration off. You have to do it via the "terminal", but you can always turn it off again by moving the mouse speed slider in the system preferences. This workes for me on 10.4 and 10.5.
1. Open Terminal (programms>utilities>terminal)
2. enter (apple-c, apple-v) the following line:
defaults write .GlobalPreferences com.apple.mouse.scaling -1
3. hit enter, turn off terminal
4. Log out and back in or restart the mac.
Happy fragging! :-)