That's more than I have - gtx560ti 1gb, i5-2400 & 8gb ddr3 with settings at max and it is generally silky smooth. The only times I sometimes have minor slowdowns is if I have my TGP and MAV up on the displays. Even then it's no drama. It will lose a couple fps and then seemingly recover. Load times are quite long in some cases, I agree, but rather that than crap fps. To add to the load times issue though is the fact that client must always DL the server file regardless of whether it's loaded locally or not. A tad frustrating but not game breaking by any stretch. There is a rumour that they are devving a dedicated server for world (KAOT has the linky for that somewhere) so that should be quite epic for the long run.
That is only for multiplayer missions as far as I can tell, having to pull the mission file from the host. Single player load times are also generally quite long, probably they are not loading the environment as efficiently as other engines, but installing it on my (now crashed) ssd, it improved load times quite a bit.
I recently upgraded my machine, but on i5 3750k with 4GB RAM and HD7870 it runs smooth as butter.