Recommended: Pentium 4 processor (3.0GHz, or better), 1GB RAM, DirectX? 9 level Graphics Card, Windows? Vista/XP/2000, Mouse, Keyboard, Internet Connection

I have exactly all those... EXACTLY

And how come I'm still lagging?

I lag very much when I face a portal, (well, usually lag alot when the two portals are right next to each other or close)

And at the glados fight, it's insane lag!

how comes?

Make sure all of your drivers are updated.

Yeah, they all are....

... can processors be updated????

What are you video settings set at?

all recommended.
High - Low - (forgot what this was, it was on the highest settings)
Reflect world and all - high - enabled

I set them all to low, but it still lags at the glados and lags a little when two portals are very close to each other.

What are your video card specs? Also, what is your portal depth set to in the options?

Upgradeeeeeeeeeeeeeeeeeeeeeee

Duffedwaffe wrote:
Upgradeeeeeeeeeeeeeeeeeeeeeee

lol wut?

If the portals lag most, it is because of your graphics card, I guess.
"Recommended" is not true, ever. My computer should run the portal nicely, but I have to use fpsconfig and my resolution is set to 640*480, shit happens.

You could, however, try the Omega Drivers, these are the best drivers for ATi and Nvidia -graphic cards.

Like I said, upgrayeddddddddddddd.

I had an integrated 6600 NVidea GeForce video card, portal lagged like shit. I got a 7800 for my holiday, portal is nothing to my computer. Hell, It can handle CoD4 like it's nothing.