This commit effectively reverses the previous one, but it's just to log that we found the root of the rez delay: the priority scheme BestAvatarResponsiveness, which is currently the default, was the culprit. Changing it to FrontBack made the region rez be a lot more natural.
BestAvatarResponsiveness introduces the region rez delay in cases where the region is full of avatars with lots of attachments, which is the case in CC load tests. In that case, the inworld prims are sent only after all avatar attachments are sent. Not recommended for regions with heavy avatar traffic!