This is an old, unmonitored thread so there was no response from FSDT. However, I can tell you the issue of the "rocks" on the taxiway disappeared after I reset the mesh resolution from 1m to 5m. No other settings changes were made.
That's precisely what I suggested to do in my last post:
is related to Mesh settings, which must be 5 meters and NOT higher
In P3D v4.5, I see the setting for mesh resolution - I'm backing mine down from 1m to 5m, hoping this doesn't negatively affect someone else's scenery... - but I don't see Mesh Complexity.
I said "Your problem are caused by having set your
Mesh resolution slider too high", and Mesh resolution is what you were supposed to change, and of course the problem was fixed. I quoted the page of the manual, which ALSO discuss Mesh Complexity, because the manual was written for FSX, in P3D it's called Mesh Tessellation, you can set it any value you like, it's not important as the Resolution, when this problem is concerned.
It shouldn't affect other sceneries. In fact, it might fix spikes elsewhere too, because with so high settings, oversampling rounding errors starts to appear, which are the spikes.