I tested it on both 1.8 and 1.9 and 1.9 seems to have a weird lag that:
-doesnt cause fps drops/lag
-Makes animals go really slow, like they move 1 second and lag other second
-adds delay to bows when shooting, when the bow is charged up, and you shoot, it takes ~2 seconds to shoot the arrow
-Makes chunks load really slow
-Basically: the client works perfectly, but the server (mobs, entites, chunks)
are lagged, the lag existed since.. idk, 1.5? but, its way more lag in the 1.9
(oh, and sorry for any english mistakes, im not english xD)
(its not my computer, 1.8 works perfect, 1.9 doesnt)