Considerable lag after entering world map. 15b

[Stormlock]

My game runs perfectly fine with CPU usage never going over 5-10% except when loading new levels, until my character steps onto the world map for the first time. After that, moving, fighting, doing pretty much anything will cause random massive lag spikes where CPU usage jumps to 50% or more for a moment. Generally happens about every 5-6 turns or so. Just stepping onto the world map and back into the dungeon, the first enemy I bump into is causing these lag spikes. In another game, same character class and everything, I'm plowing through trollshaws with no lag at all. Reloading the save file doesn't help; once the character has touched the world map, I get these lag spikes for the rest of the game. Though they seem especially bad when there's weather effects. Not limited to having graphical effects on screen either; just moving back and forth with no enemies in sight and no cooldowns or effects expiring or anything I get these spikes every few seconds.

Edit: To my dismay, the infinite dungeon has these lag spikes from the very start. Only characters in the trollshaws who've never left the dungeon seem to be lag
free. Edit^2: This might just be because the infinite dungeon seems to have a tendency to create massive mazelike vaults with tons of monsters blundering into traps constantly. I haven't managed to clear a level with these vaults on it to see if the lag persists with all the monsters dead. The lag in the infinite dungeon is much worse than the normal game, at any rate.