In the PMDG OPS documentation, there is a number of recommendations for tweaks for several sections of the fsx.cfg file. In general, are these considered high impact changes proven to improve performance or are they more like "try it and see if you get better performance", i.e., highly variable results depending on configuration specifics ?Thanks

They are pretty mild.. several are SP2 defaults. I don't have a benchmark test, but I think there's a little improvement. Right now I'm trying fiberframe setting of 0.20 instead of 0.33 to see if I mind a few blurries in trade for smoother flow... haven't decided yet.