I’m getting 30 FPS with 10x10, Epic settings, tesselation on and over 240 000 grass foliage instances (custom grass, not from LAM). I think this is a acceptable result. If u have a look on ARK, I can’t even play ARK with Epic settings over 15-20 FPS.
For sure LAM is performance heavy, but not that much you wrote.
Maybe you should play a bit with your settings, like increasing the landscape lod factor, use custom grass and be sure that your graphic settings aren’t set to epic when your pc isn’t good enough to play other games on epic.