Our learning continued. We ended up extending with Zeo again - so now running a combi of wsgi and zeo (four zeo clients).
So we changed also our #Main database cache settings
# Main database
cache-size 500000
cache-size-bytes 300MB
Still the restarts are unchanged fast although we have like 1.5 mill dexterity objects.
So we start the New Year without any of our old problems with slow restarts