ps - make sure to turn off NP reverb also! and the default templates from Dorico also seem to add a bus mixer reverb effect on top of that…so turn that off too, unless you want to replace it with Miracle.
Yes I have it on good authority that each instance uses quite a lot of its CPU power on reverb. So with many many instances you’d want to turn reverb off, also because it will mess with MIR anyway.