Hey Jonny I’m really interested to know how far you got with your testing, I think I’m working on something similar and i’ve noticed that performance fall back, but all that time i thought that I need just to modify and optimize my scene, and after a long time spend to do so, I’ve managed to really get a better performance for the scene, but not as i expected.
If your word are right and it might be the template itself i may be get some relief (because i start the project adding the project to a new level for the product viewer template - and start building from there).
I will be following up with you on that topic if someone with more exp. than me replies,
and Thanks for sharing your conclusions it helped me take some NEW considerations 