Merge branch 'release/0.80.27' into develop
migration: consume a lot of memory (we have plenty) but speed up a lot of things during migration.

In fact, I think this will just make the whole speed sustainable, instead of beiing more and more slow when we reach the end objects types (with many dependancies to other objects).
version bump for 0.80.28.
Merge branch 'release/0.80.28'