The second column in the debug panels is ms(millisecond) per Frame. The "pan" is render for panels. and "fnc" cycle time for running functions. Try to mark the points were these are highest that will show possible chock points. I don't know a method to check each one - (Timer()?)

srv - 12.4 ??

Your screen shot shows a low fps of 50 ?? This is bad? I'm sure you set a good clip range right. The scene seems way to small for turning the furthest models into sprite.

Wouldn't a it run a little faster with terrain? (maybe not)

Well all I can help with.