When we go to a class page, we kick off a whole bunch of lookups to get metadata for recordings. If we click back to go to the overview page, the pending requests are still there. If possible we should cancel them all.

Some additional improvements:

• if not already implemented, do this in batches - e.g., only open 10 requests at a time
• add a bulk lookup system, so that we can ask for 10 or 100 mbids at a time.