Is this expected to slow stuff down on db1047 - or are the queries I'm running just horribly inefficient? ;)
What Dario said is all accurate. But to answer your question directly,
yes, db1047 should be a little slow right now. Maybe a lot slow. Because Sean is copying all the data from it to db1048. This is expected to finish within single-digit hours from a couple hours ago, so it should be fine soon.