I have a farm similar to the one depicted in this video (https://www.youtube.com/watch?v=aBLEbJ9ozRA) in my single player world. The debug overview suggests that I'm getting ~50fps, however all entities in the area have begun to stutter (entities including chicken and arrows).

I've listed this as a bug because I have cow, sheep, pig, and chicken farms with a higher population than this in close proximity to each other with no negative results(a 1x2x1 space). This is isolated to 1.9 and did not occur in 1.8. It looks like it's caused by having too many aggravated pigs in one place (there was no stutter before they were agro'd, and after killing a large sum of them, the stutter decreases significantly...before they spawn in again).

Also, just wanted to say, 1.9 is awesome, love the new combat system, thanks so much for the hard work!