skipping frames like that is a sign of using a low polling rate like 125hz(am i wrong?)
i had that with my mx518 when i didn't lock my fps to hz
try again with 500hz
vsync should be off, or you would just get 119.9 fps all the time :/ so i assume it's off
you must have really small hands
get a g400, it's light and has a thin mouse cord so it'll be easy to use with a claw grip