PC client under boot camp runs worse than Mac client?!?

I've been running the Mac client for a while now, with no major issues. Highest graphics settings for the most part, with severe graphics lag only in the arachnos maps.

So I installed the PC client on my Boot Camp partition, expecting better performance. The game was so jerky it was unplayable. Even when logging in...when you get to the character selection menu, as I would mouse over my characters, there was a noticeable delay between when my mouse was physically hovering over a character, and when the game caught up and highlighted that character's name.

FWIW, this is a ~2 year old iMac, 24", with the ATI Radeon 7200 card.

Did you install the Boot Camp drivers off of the Leopard CD (or download them from ATI)? The native Windows drivers don't really work all that well.

I originally had the drivers off of the OS X cd. This morning I installed the Bootcamp drivers for XP off of ATI's website. No change in performance.

I don't really use Boot Camp anymore (I removed it with the Mac release of CoH) and I don't have any Macs with ATI, so I'm just guessing here.

Is there anything 3rd party installed like virus scanners that might be running in the background? Did you install any Apple updates like the Multi-Touch Update? Did the ATI drivers install correctly, and do they have settings that need adjusting?

While CoH wasn't bad in Boot Camp for me, it does seem much smoother in OS X. I've got a 24" iMac, 2.8GHz, 4GB, Radeon 2600HD 256MB.

In Vista I didn't notice so much lag in Arachnos bases, but the game was choppier overall even though I ran it at lower detail settings than I do in OS X.

I think it's because CoH uses OpenGL, but Vista is Direct3D. When you play CoH in Vista the graphics go through an emulation layer. I think it's possible to download specific OpenGL drivers for Vista, but you need to enable a compatibility mode which disables the Aero UI. On top of that, OpenGL drivers have a lower priority since almost all newer games use Direct3D, Direct3D the default standard on Windows, and default Direct3D is usually faster than OpenGL on Windows.

(Sorry, if I'm fuzzy on how Vista works, both the games I used it for have Mac versions now so I really don't use it anymore.)

On the Mac side, OS X uses OpenGL heavily, and Apple is constantly tweaking it. All of the eye candy in OS X uses OpenGL, so when Apple works on UI responsiveness there is usually an OpenGL tweak involved.

Basically you're just going to need to adjust your settings down a bit if you're running Vista.

IMO, CoH is now the gold standard for Cider ports, and I really think that it's use of OpenGL (which OS X understands) rather than Direct3D (which would need to be emulated) is a big part of it.