.sbsar slow

hello

when using .sbsar files in blender and unreal engine:

My .sbsar are immensely heavy with very large trees.
any change in parameters the software stops for minutes.

I heard that the size of the trees doesn’t influence anything.

Is it possible to resolve this?
both in Blender and Unreal with some specific configuration?

all the .sbsar that I create have this problem.
small or big

they do not contain displacement channel

thanks