Me and my players experienced significantly lower FPS when in urban centers and near large rocks/caves. I drop to at most 55 when in jungles, but urban centers can drop to as low as 30 and caves go to about 40.
heres my fps in more open fields.

And my FPS near rocks

In this area, when standing on these rocks near Tan Di, me and my players dropped to as low as 15-20 FPS. the moment we left the rocks, our FPS jumped back up to normal

Most screenshots were taken with a blank editor map, with only my character spawned.