takes too long to load the instancing example

[tanzfisch]

we have a design issue loading models. It can't be that it takes that long to open the instancing example

Every instance appears to be loaded separately when in fact the model is only loaded once from disc. But when we make copies of the reference scene node it takes a lot of time

[tanzfisch]

It still takes long but it's more responsive. Need a different approach then copying nodes for instancing. 0.37.2