9 JAN 2021:
This week I found the primary reason for the lag: Nested loops. One block of code alone was checking around 600 calculations. Thankfully I found a way to reduce this significantly by re-ordering the code.
With that issue out of the way, I also started work on a "new" enemy. The shield fighter. There were a few early demos with this enemy, but this new version will be completely redesigned and destructible. I'm really excited about this one because it will add a new level of strategy to the game!