It's kind of late to get into much detail, but my video card isn't as good as it needs to be.
Although the FPS stayed very even with almost all the sliders pushed to the right, for some reason I had to move some of them back to the left.
But with a lot (hours!) of moving sliders back and forth I finally found a good balance.
Throughout it all the FPS stayed steady.
In any case Prepar3d is running well and openLC has made a TREMENDOUS improvement in the two areas that I tried it in; Spain and Italy.
This is how one small area of Spain looks.
THIS IS NOT PHOTOSCENERY!

OpenLC EU gets a big thumbs up from me, although you may have to change you in-game settings a bit.