mds (MacOS spotlight indexing) was always running, and constantly thrashing. I believe this is happening because it's trying to index remotely mounted drives (which are enormous). The solution is a program called mdutil
sudo mdutil -v -a -i off # turn indexing "-i off" for "-a" all volumes (-v verbose)
sudo mdutil -v -i on / # turn indexing "-i on" for the volume / (-v verbose)
