CSS lag: halp

so, I've had this problem with lag on CSS for ages. I dont know whats causing it. When I play FEAR: Combat online there is no lag, and it runs flawlessly. Then I go onto CSS and its unplayable, constant lag. Some servers work ok, but the vast majority dont.

Oh, and the server I always used to play on (lag free) was called Nullnet, they moved IP and I lost it :( Does anyone know its newer IP so I can find it?

Thanks :)