Adam, what kind of AV/firewall software do you use? Sometimes certain combinations of SW can cause bottleneck somewhere. I’ve had problems when DKservice.exe (Diskeeper background defrag task) would go crazy loading up CPU and HDD, slowing the game (or Alt-Tab switching). Other similar issues may occur. I recently switched to Kaspersky form some free SW I had, can’t completely vouch, but it definitely has much lower memory usage, and didn’t create any performance issues yet, so I’m sticking with it for now.
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As for CPU speed, I only have dual-core 5600+ AMD and 2 GB of RAM, but since I have SLI pair of 7950KOs for a total of 1 GB of VRAM, I get very satisfying performance on all high settings with 4×AA. Aside from mysterious lag spikes (that last many seconds) that seem to affect several players at a time on a server (both in FH2 and PR, not in vanilla), occasional network lag and sometimes lag while flying the plane/copter (both in FH2 and PR, rarely in vanilla), that thing flies (no pun).
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My machine uses definately its both cpu cores while playing I must say.
Doesn’t mean FH2 uses them. There are a lot of other programs running.