The game froze up and wouldn't do anything every 2 in-game seconds or so for a while in one of the battles, replay attached. Some potentially relevant details include:
It was Skaven (player) vs. Wood Elves (AI)
The map was forested, and vision was a significant factor in the battle.
While the game was "frozen," it was still partially responsive; camera controls, both mouse and with hotkeys, worked fine, and the audio adapted appropriately as I moved the perspective towards or away from the battle/different units.
Nevertheless, units could not be hovered or selected, whichever unit card was being looked at when the game "froze up" could not be changed, commands seemed to be lost, broadly speaking.
The game still accepted some inputs in a delayed way. If I paused, either with "P" or with "Esc" (for the two different kinds of pausing,) the game would faithfully remember that input when it started moving again a few minutes later and execute it before any in-battle time passed.
Outside of when it was totally frozen, which was, again, every 1.7ish to 2.5ish in-battle seconds, the battle ran smoothly. I don't have quite beefy enough a computer that I should actually be playing on Ultra unit size, and other battles in this campaign have been affected by those limitations, but I'm pretty sure that's not the issue here.
It never froze while paused, I don't think; only while time was moving.

I misplayed the battle pretty badly, don't look at meeeeeeeeeeee.
This is not an in-game bug, but the formatting options for an unordered list don't appear to work in this bug report section, so, like [end list]
My best speculation is that some normally trivial calculation got bloated enough to freeze up the game, given the particular ways in which it froze up and the regular interval, but I really don't know.