keep in mind that it might not be anything to do with your mouse or sensitivity settings
its highly likely that it is, so try the advice from the guys above
but also look into your video settings
next time your in a match press F9
this will display your frames per second in the top right hand of the screen
red its bad, orange/yellow is kinda ok and green is good
but you want to have a min of 30 fps at pretty much all times 60 is ideal
if your dipping into the red, go to your settings in the menu
video
advanced settings
here you can turn down / off settings to gain you some frames back in your pc is struggling
biggest offenders are
Anti-aliasing
shadows
post processing
particles
if you get to low or off on all those are are still unhappy hit these next
effects
shading
environment
lastly
object detail
texturing
another way to do it is set everything to lowest and slowly turn things up until you get the best balance between looks and frames
also a note, when your testing your frames if you drop into the testing grounds your frames will be way higher than what you get in a normal match , so test in testing grounds and get it nice, then you should be ok in proper matches
lastly
there may be nothing wrong with your settings at all, mouse or video or what ever
this game is super hard, most people come into it thinking that they are a fps god in call of duty so they will smoke this game
wrong, its rare to see new players getting more than 50 damage in their first few weeks , no matter the build or mech or fps experience, its a hard game and takes a lot of practice and patience
dive in and enjoy
*EDIT*
forgot to mention
set your video settings to display as full window
the game / cry engine prefers this method and you will see increases from it
also match your resolution to your desktop settings or if you need to lower it for frames then make sure you choose one with the same aspect ratio
Edited by Naduk, 15 September 2015 - 02:30 AM.