While testing my 1.9 adventure map, in recent snapshots there has been extreme network lag. My fps is just fine, the problem is that when I hit a mob, it takes, like, five or ten seconds for it to register, and all the other mobs move really, really slowly. Other effects include redstone repeaters having a much longer delay (often, taking about four or five times as long to delay), players regenerating much slower, and shot arrows will barely fly any distance at all. Essentially, the world around you slows down, but you can still move at normal speed.
This is likely because of all the complicated redstone and command block systems that exist in my map, so something should be done about this, otherwise most complicated adventure maps in 1.9 will be unplayable.

Steps to Reproduce:
1. You will need a complicated adventure map with very complicated redstone systems. There likely aren't many 1.9 maps out there currently that would trigger this bug, but I cannot upload my own map here because it is unfinished.
2. Go in, and try to play it. The effects should soon become apparent.