CPU issues

[sorry for grammar and punctuation's](Windows 7 Home Premium)Processor Intel(R) Core (TM) i5 CPU 650 @ 3.20GHz RAM 6gb 5.68 usabel system type 64 bit operating system )(Back story) im playing this game on the computer and i get random lag spikes most of it randomly or when i click on a enemy to shoot it freezes or if i shoot and im in a bush i set the graphics ass low as i can and added mods to even take out other things. then i just noticed it says high cpu usage 100% of at least 1 CPU i went to my system config. and disabled a few things that this website said that i should do but it is still happening. (could it be i need a graphics card? I have a Intel (R) HD graphics) their has to be some other reason any help would be appreciated because i have been having this issues for atleat 4 months and it makes me not to want to play the game.