Hi all,
I seem to have got my sytem's "stutters" under control and thought I'd share a little of what I learned.
The problem:
I was getting framerates of 50+ though quite erratic but then I'd pan the camera or pull a sharp manoeuvre and I'd get horrible, very brief fps stutters where the image would breifly freeze, jump then be fine until the next manoeuvre.
What works for me:
I had a look at his page: http://www.prepar3d.com/SDKv2/LearningCenter/getting_started/performance/general_performance_tuning.html - tweaked a little didnt really know what the effects were but got a better understanding of what these entries in the cfg did.
Then I looked at this page: http://www.venetubo.com/fsx.html - uploaded my cfg, was not confident enough to paste their suggest cfg file in full as it seemed to not really account for P3d 2.2 but i did however pate the entries it said it had ajusted into my existing Prepar3d.cfg.
-- this helped a bit but didnt fully solve the issue
Then looked at my Gfx card's control panel. For me, I have 2 crossfired AMD FirePro GPUs (it's the new "trash can" Mac Pro)
Here I turned everything to "use application settings" as everyone suggests, turned off "wait for verticle refresh" and "Open GL tripple buffering" and this made the biggest difference; I turned off AMD crossfire's "Frame Pacing"
Now almost smooth as silk 40+ framerates in a nice addon AC at a nice Orbx Airport... happy days!