Why did frames per second drop after computer sleep

I don’t know why this happened: I put a bunch of grass on a hill and when I played with occlusion culling, it was 40-50 frames per second. I was happy and let the computer sleep and when I came back to play, it was 3-7 frames! what happened and how can I fix this?

Oh , I forgot, when I erased all the grass, the frames were still very low, about 8-10 frames. no trees, and just terrain and fog. I don’t know what is causing the lag.

Thanks in advance!

save scene and restart unity is probably your best bet, use the profiler to see what’s causing lag.

I checked the profiler and it said 64% camera rendering, so I guess it is all that grass. Is there a way to keep the grass and raise the quality?