Charlie, I ran some diagnostics and like you, I noticed that the game uses around 2Gig of RAM and also utilises around 50% of CPU power - its not maxed out at all for my system specs. I use process lassoo as well. My CPU is overclocked; from 2.6GHz to 3GHz, dual core AMD 5000+. Its plenty fast enough, although I am running a 32 bit OS, which I believe may affect performance.
As I stated on an earlier post to these forums, I turned off ambient occlusions, low sky, low water, no shadows, kept on HDR, and high for effects and model details. In Nvidia control panel I forced 2x AA as someone had pointed out on another thread. Ok, it still lags when there are things happening, when it gets kinda hot etc, and if it is too much then I go to half speed; also seems to add more stability too with this speed, as experienced less CTD's using this method. But it is still far from perfect.
It seems that it is difficult to pin these 'issues' directly to CPU - especially if higher powered, quad core 3GHz+ systems are struggling. I would love to buy ToW3, the campaign element looks interesting, but if it plays as bad, or maybe worse as Kursk then I shall pass. Sorry.