YMMV but I seem to realize I’ve done quite a bit of fiddling with reducing CPU myself. I recall that with some VSTs or even KONTAKT instruments you can get higher CPU happening with the built-in effects than with some external effects particularly reverbs and the like.
I recall turning off the internal reverb of a synth, and instead sending it in Gig Performer to the Global rackspace that included the MeldaProduction MCharmverb VST. It seems to be very efficiently coded and I noticed a significant drop in CPU (although I can’t remember the details). This will probably vary a lot too with the parameters you need for the reverb sound you want.