Recently downloaded and started playing Minecraft 1.8 after a bit of a break from 1.7. The game still runs perfectly smooth for me in the sense that there's no movement lag, everything loads fast and fine, and I'm keeping a consistently standard fps that I'm used to (around 20-30fps).

However, here in 1.8 (and in 1.8.1), mobs seem to be severely glitched and prone to bad lagging, especially hostile mobs. I can attack a zombie, for example, and he'll get knocked back almost in slow motion, then he'll almost freeze in place like he forgets to attack me before finally coming after me. Some other examples is walking up to a spider or a skeleton, only for them to take a good 5 to 10 seconds to finally notice me and start attacking.

I've heard this is possibly caused by ticking issues with certain entities, and I tried using /gamerule doMobSpawning false, but it didn't make a difference.