Landscape spline performance questions

I have the idea to use a pretty heavy static mesh (4200 tris) in my landscape spline and I think I need to convert the output to instances. The spline meshes are not welded, so I could put them in a blueprint as HISM’s. My question ist his: will UEFN treat the differently curved, but otherwise identical meshes as instances of one mesh or do I end up with dozens of different ones?

Also I am wondering how UEFN generally treats landscape splines performance wise.