How did I miss this little nugget of awesomeness in 3.4.2?
“Production Mode is no longer needed in the platform. The system now refreshes the cache automatically when working in builder tools, removing the need for repeatedly loading metadata from the database. This eliminated a huge overhead on the database. (Tri-142286)”
Does anyone know definitively after loading OM packages if we should clear the cache?
No need. The system clears the cache when the import completes.