Possible way to improve performance moving large hierarchies?

In our project we have objects that consist of many child objects (i.e. object with ~2000-3000 childs). The childs are pure transforms with meshrenderers.

We noticed the following: Moving and rotating the root-object will consume more cpu time the more child objects are parented to the root-object.

In example to move and rotate such a hierarchy transform.position and transform.rotation has to be called, which both consume about the same time.

Are there any possible ways to get around this or speed up the process?

The short answer is: no.

The long one:

When moving the root object, Unity needs to move all theirs childs to the relative position (the same goes to rotating and scaling). So, no, there is no way to “speed up the process”, at least not one that doesn’t relly on a new CPU or overclocking the one you already have (and even doing anything like that, the difference would not be that much).

One thing that I would reccomend is to not parent that large amount of objects to the same root one when you know that you will need to move the root one.

Also, the only reason I see to parent ~2000 objects with meshrenders to a commom root one would be to organize the scene, but a good practice is to keep the root one at the (0,0,0) JUST for the sake of keeping the hierarchy organized, not for moving that amount of objects at the same time.