PLEASE CHECK THE VIDEO FIRST!

https://www.youtube.com/watch?v=Vty2f53Ocfc&feature=youtu.be

Since 1.9, massive entities (+400 for me, depends on your computer/server) cause extreme lag. Killing the entities fix the lags. A moderator locked my old report without looking the video. By entities I don't speak of mobs only, but Boats, Item Frames, Armor stand and that kind of stuff that don't asks the server the pathfinding. I tried to do the exact same thing in 16w14a, that corrects the pathfinding lag, and it does the exact same lag. It ISN'T the pathfinding lag. In 1.8 there was no lag despite the entities.