GC extremely huge hitches in empty map

[ThiloN1987]

@MostHost_LA

For me, The itches seem to be due to tessellation on the landscape.

Glad you spotted they have to do with garbage collection Though.
something must be wrong with how the landscape is removing tiles?

The map is completely empty. There is nothing in it. No actors, no landscape. In a new UE4.25 project there are also spikes, but not so big ones (second image).