We were cruising right along until a few hours before the due date, when we started getting unplayable levels of performance issues. It turns out I accidentally changed the pathfinding to recalculate each physics tick for every spawned enemy. Not a difficult thing to fix, but it sent us all into a panic right before the deadline. I wish I had a bit more time to optimize, there's still some occasional stuttering and performance issues, but overall I'm really happy with what we ended up with!