What is problem!? I have nvidia GT440 (1gb), Intel[R] Core[TM]2 Duo CPU E7400 @ 2.8 GHz, 2gb of RAM.
-In game I have 100fps (vsync off), when I press console button my fps down slowly, and I press 'servers' and 'game info' be like this (on pic) http://www.dodaj.rs/f/38/3w/KuGwB1n/koji-kurac.jpg
Check if your pc have to install some updates too! maybe you download some programm and is working behind the pc or scan your pc with good antivirus system to clean it up! also check your hardrive c: maybe is full or need clean up too! or format the pc!