Why is my BeamNG.drive lagging when the stuff is rendering?

littearly, i don't know why, but my computer lags while rendering vegetation and buildings, and the framerate drops from 45 fps to 3 fps
the computer (or laptop) specs are:
-AMD Ryzen 7 3750h with radeon vega graphics
-NVidia GeForce RTX 2080
-512GB SSD
-16 (or 15.4GB as the system thinks) GB of DDR3 (i think) memory.

 

The same thing happens to me. I just wait a minute or two.

 

This sometimes happens to me but it isn't a persistent problem so I wouldn't worry about your specs; it's probably just the game.