Why does my laptop with 4gb ram and 500 gb hard lags in games like call of duty or combatarms?

I have a laptop exactly the same, but I found that it's not always about the memory size, there can be lag problems...
- If you are playing with it on your lap, it will shake often and find it more difficult to play
- Sometimes there is just a problem with your internet (I have that problem a lot)
- The playing speeds will ultimately depend upon the quality settings (visual quality, audio quality etc.)
Good luck finding the problem!