What does the process 'Locum' do?
Google says that it's a helper process for Finder, that does all the stuff Finder would need escalated privileges for.
In addition to what's said, if you choose to "Secure Empty Trash..." in Finder, Locum will consume a lot of resources because it will re-write the data (possibly several times) of where your trashed items resided. This will ensure you can never ever recover them.