Bug:
There seems to be much more ticks per second lag in 1.12-pre6 and pre7 compared to the TPS lag in 1.12-pre5.

Possible steps to reproduce:
1. Create a command block contraption in 1.12-pre5 that will cause lag (such as /testfor @e)
2. Load the world into 1.12-pre6 or 1.12-pre7 and compare the amount of lag it causes to the amount of lag caused in 1.12-pre5