This mod gives makes two things configurable. Control how fast villagers can breed and whether villagers can change profession once they have chosen a profession.
Each individual villager becomes more valuable when villagers can not breed. Even more so if they can not switch profession when a player wants it. Additionally large trading halls are discouraged which in effect also can increase server performance. This gives players more incentive to explore the world to find more villagers.
Only needs to be on a server.
