A Phenom II 555 is a dual core model if I remember correctly. This means it’s pretty much expected that you’ll be heavily CPU bottlenecked and your CPU will be pushing 100% load a lot (or even all) of the time – a max of 30fps sounds about right to me, since that’s very similar to what most core2duo users cap out at (unless they’re running high overclocks).
Your options to improve performance basically come down to:
1. overclocking, provided your cooling is sufficient or you are able to replace it
2. upgrading to a Phenom II X4 or a Phenom II X6, provided your motherboard supports any of these
3. going the whole nine yards and upgrading to an i5 sandy/ivy bridge with a new motherboard (and possibly RAM)
With these choices 1 is the cheapest and 3 the most expensive (although getting a hold of an X4/X6 processor may not be cheap either since they’re out of production), but the amount of improvement you’d see in terms of minimum framerates would also be the best with 3 and the least with option 1.
If you don’t want to spend too much money, but at least get above 30 fps most of the time then the Phenom X4 might be the best compromise, especially if you can get one cheaply somewhere. You might also want to get a decent aftermarket cooler with it so that you can overclock it to squeeze out some extra performance.
Just bear in mind when deciding what to go for that this game doesn’t perform flawlessly in WvW or really busy dynamic event even with an overclocked i5 like I have (I get as low as 15-25fps at worst) – a better processor does reduce the severity of those FPS drops, but it doesn’t eliminate them completely. The Phenom X4 or X6 will net you decent performance for the most part and should give far better results than your current X2, but for the best results when it comes to absolute minimum fps an i5/i7 sandy/ivy bridge is recommended.
