I have a mid range rig and I installed Skyrim flora overhaul which should be equivalent to Tropical Skyrim and it didn't decrease my FPS by more than 3-4. Check out Skyrim Project Optimization, Hi Algo Acceleration Booster, Realistic Lighting Overhaul, and Low Res Pines and Aspen Trees. Those combined boosted my FPS by a lot. I mean a lot.