windows freezing and lagging after play skyrim and dota 2 games

Hi ti all

I have strange problem with my new pc that really bother me.
after playing for example 3 hours skyrim game when i close game the windows 7 is really slow and has too lag too.
i must w8 3 or 4 min to it recover it's speed.
i bought this pc last weak here some information of my pc:

CPU: Intel 3570k i5
VGA: EVGA 560ti OC
RAM: 4 GB crossir GT 1866 OC
MAIN: P8Z68-V PRO/GEN3
POWER: cooling master 650
CPU FAN:Tuniqe Tower extreme 120

and about hardwares temp when i am in game:

CPU : 54 C
VGA: 70 C

The temps look all good, same with the specs, also virus's can cause slowdowns in computers, have you tried scanning your computer for virus's? And do you have any other programs open while playing/closing games?

Since you said you recently bought the computer,first thing I would do is update the drivers for the video card and any other components in the machine,also updating windows 7 through windows updates all the way through can also fix performance and other issues in the windows operating system. The load temps seems to be normal though a little warm and could be better but nothing too drastic, make sure your computer is getting enough space to blow the air out with the fans and isn't to closed spaces were it would be hard to get rid of hot air from inside the machine.

i have eset smart security that always updated and installed it before connecting to the internet but i i will scan.
my windows updated and about drivers i updated most of them i think., i have newer nvidia alpha driver too.
so i install beta version and see anything change or not.

beta version invidia driver installed.
no different.
someone said me about dota 2 bug that fill system memory and make windows full of lag.
the good news is that when i close chrome before going to the games it dosn't happen anymore i think.
must check more to be certain.