Large Distribution Database with frew Rows

I have a distribution database that has grown over 50g. Distribution cleanup takes over 15 hours to run and there are always very few rows in msrepl_Commands. Usually only a few hundred. Everything is being replicated fine, but I fear a storm is coming. Anyone know why distribution would be so large with so few rows? Also, Ghost Cleanup has been running all week, so I'm thinking maybe the records marked for deletion aren't being deleted?