BadBud, I detect minimal, if any, fps hits with A2A stuff, including the Spit.
I have an old laptop, and other than a texture lag when jumping back into the cockpit from an outside view (which I have with all A2A aircraft), maybe 1/2 to 3/4 of a second?, everything is very smooth.
Processor Intel Core 2 Duo P8400 2.26GHz
Windows Vista OS Windows Vista Home Premium 64-bit with SP1
Hard Drive 320GB (7200RPM)
Screen Size 15.6" HD (1366x768)
RAM 4GB DDR2 667Mhz
Optical Drive DVD SuperMulti with Light Scribe
Direct Disc Labeling Yes
Graphics Card NVIDIA 9800M GS with 512MB GDDR3 VRAM
BTW, here is a "tweak" site that has worked WONDERS for myself and others in FSX. Best thing is it's automatic. Bojote's Tweaking and Tuning Tool for FSX
It's really magic, I went from stutters and unflyable to smooth as silk!