There seems to be a bug in the system that detects doors (houses) in a village. The same "real" door get's constantly added as a new, additional door in the sense of village buildings. This does not only effect villager breeding and golem spawning, it also causes a lot of lag and memory usage.

Steps to reproduce:
-Open a world in 14w02c and go to a place where no interfering villages are arround (easiest option is a flatland world with no structures)
-Place a villager and a door with two blocks above (to make it a valid village door / house)
-Wait for a few seconds (while doing that you can watch the memory going nuts in the upper right corner of the debug screen)
-Save the world and look at the stored NBT data for that village

A few screenshots:
Fresh world, no doors placed yet: http://imgur.com/923NTQJ
After placing one door and waiting a minute: http://imgur.com/7fWJBi6
After placing four more doors and waiting another minute: http://imgur.com/AJsAhab