Are you working on particularly large orchestral scores with large sound libraries? I could see the latter having a notable impact on the ram load.
FWIW, I have an old mac mini (2014) at work with 16gb ram. I never have problems (apart from playback buffering which is more a limitation of the old, weak CPU than the ram).
Further still, I have an (almost as) old imac at home with 32gb ram, and I can run Hauptwerk (very large VST with pipe organ sample libraries that can take up to 148gb+! of ram depending on the sampleset) and run a sampleset that takes 28gb ram and run it in parallel with Dorico no problem. So that’s 28gb to HW, leaving only 4gb ram for the operating system and Dorico. All within 32gb.
Also, have you tried opening a project that has the playback template set to “silent” to see if that makes a difference? I guarantee you that heavy ram load (if the utility is even measuring the pressure correctly) isn’t from Dorico itself.