I've had a similar problem recently - sometimes my mouse would work kinda ok, and other times it would just get really sluggish.
I just discovered what the problem was for me, and it was quite surprising; it had nothing to do with any software, but rather my mouse pad. I tried moving the mouse on another surface, and it moved fine - it was only on when I moved it on my mouse pad that I had the problem.
Temporary solution: I took a book from my bookshelf that had the perfect surface it seems on it's totally black covers - using the book as my temporary mouse pad, my mouse now behaves normally.
I'll have to get another mouse pad, one that's totally black, apparently.