Flamingskull,
I have CFS3, ETO, PTO, DPC/KS, CFS3 Firepower, and CFS3 BOB installed. When I modify settings in my config. utility, I usually have to run the utility for each individual installation to be certain the settings are as I want them to be. I generally have to run the config. utility after installing the major expansion revisions, and whenever I update my GeForce drivers.
I have a Core2Duo and a GTX275 896Mb GPU, and I still can experience low frame rates in busy or densly populated areas of the sim. I have the settings in my config utility jacked way up, and tweaked the bejeezus out of my composite scenery and composite texture budget xml's in the assets folder to push the graphics detail and quality as high as I can get it. What I have done to keep frame rates at a livable level is to reduce the major densities down quite a bit. Your frame rates will pick up considerably if your system isn't completely overwhelmed by the sheer mass and volume of the details it has to render graphically. I start with a density of 0.000025 and climb no more than 0.000025 each level....some people might suggest other ways of increasing speed, they like to have cities look like cities, not like a 1 horse ghost town with hardly any buildings...but I prefer to trade quantity for quality....
Hope that helps you,
Enjoy