Windows 7: Lag on all Games i've played

I used Acer 4741.I have Orc must Die,The Incredible Hulk,Warcraft III,Angry bird,Plants vs Zombies, and lots more small games on my laptop. even ANGRY BIRD lags for like 2-4 seconds and returns normal everytime i play it.I have use Ccleaner and Advanced system care Pro and it didnt helped me. Any more suggestions??

If your computer is lagging on PvZ and Warcraft III, then I'd say either reinstall your windows, or make sure you have all of your drivers up to date. Those games hardly require any performance, and the specs that i have seen for your computer should be able to run all of those games perfectly fine.

Heat also can cause laggy games because the hardware isn't cool enough to run properly, and it'll start to screw up.

my cooler inside is dusty, could that be a problem?? my laptop easily heats up...

It'd be a good idea to keep your PC dust free. It's a good idea to check your PC for dust. Though it takes a while for the dust to collect (unless you're in a really dirty/dusty area).

Edit: Dust can cause all sorts of problems.