Mine goes down to 20 in the most densely populated areas and areas with aftermarket sceneries (boston, cleveland, phoenix). I too can't get more than 9fps at TNCM (Princess Juliana/Saint Marteen).
The thing I dislike most about FS9, is that it was written in late 2004, WAY before any of the newest video card features were even concieved. Most of today's games are more dependant on the graphics processor. I get the same framerates when Anti-aliasing and Antistropic Filtering are on and off, which tells me the framerates are limited only by the processor, and not the graphics card. I'm experimenting with overclocking my new chip over the next week or two, so I'll take screenshots of the same place at different clock speeds.
I DO look forward to FS10, which will (hopefully) take advantage of the newest graphics card features (Pixelshader 3, SLI), as well as support multithreaded (dual core) cpu's.
[Edited 2006-01-22 22:08:36]