not really a tutorial but just a fix that will hopefully help a few people.
The MW3 process using to much memory, game stutters.
Check with the Windows Task manager how much memory Modern Warfare 3 is using. When it's more than 2gb this can be the cause of the stuttering. Go to the MW3 players2 folder, open up config_mp.cfg and set seta r_preloadShaders to 1 and seta sm_maxLights to 0 and make the file read only so it doesn't revert back.
if you need help with this just ask me, glad to help out