This is False, I’ve been scattering gigantic forests with no problems 
Perhaps you are working with an enormous instance count without realizing it?
However, when changing value sliders geometry node can be felt significantly less reactive compared to the hair system, and i believe the instance count before blender can be felt laggish is a bit lower than usual, i need to do some tests to confirm.
I can confirm that there a lot of un-necessary evaluation happening from time to time, especially when working with objects/collection pointers