Lag Prevention Options

[kowbrainz]

Was trying to set up some events this afternoon when I noticed my game was suddenly lagging a whole lot during "Battle Processing"; a wait time of 3+ seconds before the enemy event would even turn to face the player.

I tried opening another project to see whether it was the project or my PC -- other project was fine and loaded a battle in a split second.
Tried making another map with nothing in it and making a battle event there -- still lagging. I even deleted all of the custom scripts in the game, but to no avail.

Really not sure what's going on here, whether my game's just grown too much and I have too many maps now or what. Are there any scripts users would recommend to combat this, or does the root problem lie somewhere else maybe? :/