I haven't downloaded the patch yet, still in offline mode because my hardware firewall does not get along with Steam. Something that has been bothering me about the last patch though is the mouse lag, I never use to get mouse lag until the last patch. I have read that turning off V-Sync will fix this, and yes it does work for me. However, I don't want to sacrifice V-Sync just so that my mouse will work properly. I hate screen tearing, it makes me nauseous and thus I have been playing with V-Sync turned on in spite of the mouse lag and its VERY annoying, it makes the game unplayable in some instances. I hope they fixed this with 1.5.

This was fixed a long time ago. I can't remember which version, probably around 1.2 or 1.3.