[QUOTE=Slavq;450205]
About exact amount of drawcalls, I’ll check this with single tree today and let you know what’s the average value. I assume that it for sure generates more drawcalls than regular static mesh, due to its dynamic features - each single tree always remains adjustable, so e.g. every branch is a separate component. I suspect that most of the drawcalls will come from large amount of spline static mesh components, because they can’t be instantiated.
Thanks! 
[/QUOTE]
Go to editor prefs > Experimental, enable actor merging.
Then select your actors (your spline based awesomeness)
go to window > Merge actors
Now your spline based thingy is just one static mesh, ready to be placed around multiple times.
Might be interesting once its out of experimental, to show how to do it. might be a big selling point later on!