Units frequently pause after killing an enemy unit

I really don't remember this happening in the non-HD edition. A unit will die, and the attacking units will freeze in place for a long time. Seems to be happening to both the AI and myself. Other enemy units could be attacking the frozen units, but they just stand there and take it. Sometimes they react, after one or two blows, but the fastest way to fix it is to attack-move.

It's like the troops are brainfarting in the middle of a melee. Is this common?