Totally agree on what swurvin has said so far.
I used to create missions with probably a thousand manually placed down items, creating a cave system like the one shown in this video:
As you can see for pretty much the whole video a group of 40 people moves through a system of caves made from vanilla rocks that I spent few days manually placing and turning them into SimpleObjects.
Because of this, everybody had pretty decent frames throughout all the operation.
Whereas yesterday I wanted to do something slightly bigger than our normal ops where we just have a few trenches down and decide to build a tunnel system with I guess less than 100 pieces.
Without the ability of turning them into SimpleObjects it was simply unplayable, ever since this feature was removed I can't create custom scenarios anymore.
I also remember another mission where I just bunched together less than 50 rocks but having 15 people walking onto them without them being simple objects caused the fps to drop drastically, again.
Didn't know about this function, I will give it a try but as I just read on the page:
But if it does a 1/10 of what the old SimpleObject checkbox used to do I'll definitely give it a try.