2) Waiting-queue logic has been rewritten. I believe there will be not much of a perceived performance improvement but we managed to cut the relevant code length almost by half and simplify some bits.
3) We have fixed appstream meta-data building - a bug that also influenced forking. When a project was forked the rpm re-signing process kept looping. Other actions were blocked by this. Hence, in addition to fix the root cause (the meta-data building), we also needed to fix the forking logic to handle the errors better.
4) We have introduced a first bits of support for modularity
So that's it. I hope COPR will serve you well.