Intel Pentium 4 processor. I have DirectX 9.0. I use Windows XP home edition. I remember updating my graphics card it was like NVIDIA, ATI, or some GEFORCE. I'm pretty sure I have around 1-2 gb ram. I don't know if this helps, but when I press ctrl+alt+delete and task manage opens up, the PS CLIENT says around 150-170k. That's pretty high but I don't know... Thanks.

I already know what the problem is.
I encounter the same problem as you.
I am also running Windows XP and have a Nvidia Geforce-videocard.
The current lagging for me is caused by the Nvidia Geforce-videocard.
The developers will make a cure for it, when they found the full problem with the videocards.
We only need to wait for now, till the fix is there and accept the horrible lagging for now.