I would think from a high level architecture view you would be better served running your database on a different node and doing a read every X seconds for display on the mirror. You could run the system stats module to monitor cpu and volatile memory management while testing various approaches, but if you accrue historical data very quickly you could exceed the storage limit on the operating partition and cause performance issues.
My understanding of hardware/software architecture is a bit dated, however, so someone with more experience on node.js, electron and the various bits that support the Magic Mirror application may have a better response.