I think you should explore some of the alternatives every once in a while, or just maintain a free plan and like 1 folder. Just checked activity monitor and onedrive only uses ~60mb of more ram on idle at least, although (and I believe it's since been pached) it had a memory leak bug at one point and would start eagerly consuming my 16gb of ram if left unchecked. The fix for that was just restarting one drive after startup, no big deal. Even on big syncs (I did ~250gb one time) it syncs about as fast as my upload speeds go and didn't seem to bog down my computer at all.