This seems like some information I can work with and see if I can get the same results. With foliage, no matter what build, it’s always important to set culling distances for your foliage and if you have a lot that are all casting dynamic shadows that can be problem that kills performance as well.
When I’m back in the office on Monday (Pending weather bc it’s apparently may snow here in North Carolina and that will shut the area down. We don’t deal well with snow!) I’ll be able to run a test with some foliage I have from SpeedTree and with LPV. So no need for the map. I’ll get back to you and let you know what I find when I can.
Thanks for your patience! In the mean time to keep working you could just turn viewport real-time off so that you can build and no worry about the FPS chugging.