Have you ever tried overlocking your CPU? Personally, I have a Macintosh Laptop, and an Intel Graphics Card, so its not very possible for me to overclock, but I heard its done miracles for other people!
Also, RAM can also be bad if you allocate too much. RAM is basically just to keep the game running, not for it to run better. If you allocate too much to the game, your computer doesn't have any RAM to support what it needs to support, so you start lagging not from your game, but from your computer.
Hope I helped,