Slow performance Blueprint with many meshes (2500+)

Why is a model with 2000+ meshes, embedded in a Blueprint become super slow to handle? If it is just an actor it handles great, but once I make a Blueprint of it, it becomes very slow to select a child mesh within that Blueprint. It takes a few seconds to show the actual selected mesh in the viewport. It seems this problem already exists for many years, so I would expect that by now it should be solvable. As long as it is an Actor it all works fine, but the second you convert it to a Blueprint, the speed is gone.