Messing aroudnnd with mongojs to replace mongoose. A test to retrieve all 10k issues five times using mongojs took 90 seconds; mongoose took 240 seconds.
Turns out mongojs isn't any faster (and is somewhat slower) than mongoose when retrieving unfiltered issues.
Added indexes where appropriate. Added another 50000 issues and despite that, the issue list is much faster than it was.
Added tests pertaining to performance tweaks.