I am running AMD XP 2000+ (equiv. to 1.4Ghz true clock speed)
Windows XP w/ 1 GB RAM
ATI Radeon 9800 XT (256MB RAM)
DSL
I tweak the sliders a lot in game. If I am dogfighting, I set for max performance, If I am GV or JABO striking a field, I set for max detail. When Dogfighting 1vs1 at alt (say 10K AGL) I get steady 74fps (with 5-10 planes at alt, I might drop to 55-60fps), if JABO diving on base I can drop all the way to 23fps or so. There is no single setting that will probably give you the best performance and detail for every situation, unless you have a really high end CPU running 3.0Ghz+ with the RAM and Graphics card worthy of that kind of machine.
I agree that the stutter will probably be rectified at some point. I just recall the WWII Online beta back a couple of years ago... When I dove into a GV infested area with a Stuka, the updates to my desktop froze my machine down to less than 1fps. It literally required several overflights of the area to get the updates over with so that I could dive in without augering.
Remember to keep Vsynch locked and remember that your frame rate is capped by your monitor refresh rate (i.e., if monitor is set to 1024x768 and is running at 75 Hertz, you are NOT going to actually experience over 75 fps - no matter WHAT your Ctrl-I display says. The Hertz setting of your monitor is a "topped out" limiting factor). You will have to set your rez and screen refresh rate (hertz) in Windows before starting up AH2 for AH2 to give you the benefit of the higher framerate.
AH2 is, so far, a remarkable transition to a new graphics engine without the nightmares it could have produced.
Hang in there !