Since you’re now bouncing all your drum tracks prior to mixing, you might as well go the whole hog and render everything else in your projects as audio, too. This is actually good practise for a couple of reasons beyond just taking the strain off your CPU. First, converting virtual instrument tracks to audio for mixing kills the temptation to fiddle endlessly with sounds that you should have largely settled on by that point in the production process. And second, rendering every channel dry (with faders at unity) and/or ’as mixed’ at the very end of a project creates a future-proof archive of it that you can return to for remixing years later, without worrying about plugin obsolescence or compatibility issues.
I wish I had rendered tracks with effects to save with old projects. I didn’t. Re-visiting them is hard to do since “things change”.
My current practice is to make a new “alternative” to my project and bounce all the tracks in place. This gets me tracks, buses, and stems. If I want to re-visit the mix I just open the penultimate alternative and get to work.