Sounds like a common complaint regarding gaming performance I hear about from coworkers all the time. People have their Dells and such, with their Intel-based motherboards and the integrated "Intel Extreme Graphics" hooked up to some uber-resolution flat panel, and they wonder why pretty much anything 3D-related lags so easily.
Until very recently, the only thing "extreme" about Intel integrated video was that it was extremely bad. And, the saddest part is that a huge number of these OEM boxes using Intel-based motherboards don't even have a PCI-e slot for an aftermarket graphics card upgrade. Or, if they do, you often need to use a low-profile graphics card, and that limits your range of choices quite a bit. There are a few (relatively speaking) higher performing low-profile cards available, but then one often runs into the other brick-wall with these OEM rigs; many have sub-300W power supplies. Not to mention that many times, the motherboard, power supply and case form-factors are some proprietary design that defy any sort of piecemeal replacement as a workaround. And, if one throws most laptop-quality 3D performance into the equation, well, that is just too frightening to even discuss...
Unreal Engine 2.5 is single-threaded as far as I know. I have a bazillion rigs here, and I've seen very good performance from some very 2006-ish hardware in KF, (e.g., 2.2GHz Athlon64 3700+, GeForce 6800GT), providing one isn't maxing-out every image quality setting and/or using a 1920 X 1080 monitor. This isn't my primary KF platform by any means, but I've noticed essentially no stuttering whatsoever, even in some pretty intense rumbles. (Although KF-Departed occasionally tests this combination ever so slightly.)
Any server that prohibited the use of one or more perks is ridiculous. OK, I suppose one is entitled to use one's "house rules" on your own server, but curtailing the use of certain perks seems pretty heavy-handed. What is next? Mandatory low-grav insta-gib?