The patch is here

[Marquis of Roland]

Night battles remove reinforcements for both sides. Maybe this isn't the case if both your generals are night fighters?

Its an error message that pops up and says the cpu is too slow. This didn't pop out before. 1.8 processor

[Wizzie]

That's understandable, the minimum required processer is 1.8, so it'll only really run the game on minimum settings, including army numbers/graphics (night battles are more graphics intensive than daytime battles?).

[Marquis of Roland]

Is there any way to change this aspect of the patch back without having to reinstall? Before the patch, I could play these multi-army battles with only moderate lag so I imagine my computer should be able to handle it, just the game won't let me anymore

[katank]

That has nothing to do with night battles then. I occasionally ran into this myself prepatch.