Here's a new config I've ben testing. Without a 400MB BF I do get stutters at perth but since I don't fly there I'm tuning for the places I do fly.
So far the best overall experience I have found is to use the FPS Limiter tool along with the cfg tweaks. This gives the ability to limit fps while staying with an unlimited setting in game, which means you don't have to take the framerate hit associated with the in-game framerate limiter.
When I use the limiter it runs a few fps higher than what I set it to, so I set it to 25 which tops out at about 27-28 in game. With the new config I'm able to fly around Redcliff averaging 25-27fps with occasional dip to 23fps, but no lower, which is impressive to me.
Using the limiter makes it even smoother and removes even more stutters, especially if you are getting a framerate above the limit you use, and even if you drop below that it's just as smooth or smoother than it would be without the limiter.
It seems the ratio you use with the max per cell tweak can affect framerate. For example 2200/1600 gave me 3fps less than 2200/1700. I've now got it set back to the default 3/2 ratio which works well for me. As you can see from the images, even with buildings at 1600 I get 100% buidling coverage when using extremely dense.
Another tweak I've been playing with is the Fiber Frame Fraction Time. .44 seems to be the best setting based on my testing around Redcliff. Also with BF down to 300MB I'm able to run my TBM much higher, which seem to help with texture loading.
To get framerates in the 25-27 range with a minimum of 23 using extremely dense I have all AI and traffic turned off, clouds at high/60mi, and aircraft shaows off. I bet the above config would work well on Core 2 systems using very dense.