World temporarily freezes if a mob is hit with a sword with Knockback 32767

Don't do that.

...Probably because the game is trying to apply physics to the mob so fast that it doesn't realise that the mob went into unloaded chunks for a few moments. If it hits a wall/other barrier, it's probably more to do with inefficiencies in velocity calculation (which hasn't been changed much since Notch made the very first test version of the game)

Unfortunately, large amplifiers of enchantments/potion effects aren't supported.

Right, see MC-10755

At least it wasn't a duplicate (2nd non-dupe issue I reported in a row)