This doesn't happen all the time, probably 50% of the time when booting the system.
The mouse will not be fluid, neither will scrolling, moving/resizing windows, etc.
I can bounce the box and everything is back to normal.
I did a fresh install of Mint 15 today.
I went so far as to disable effects in Cinnamon. Doesn't seem to help. This is literally immediately after booting, even at the login screen.
It seems random.
Cinnamon 1.8.8 | Mint 15 64 bit | nVidia 310.44-0ubuntu2