This is awesome!! I'm surprised at how many upgrades you were able to implement and how balanced the whole game is in general. I really hope that you polish this up after the jam ends.
The only downside for me was the graphics, so I thought I'd offer a few recommendations. I noticed that you are using Godot: look into themes. They're an easy way to change up your buttons and GUI from Godot's default gray style. Regarding the lag, I suggest decreasing the number of drops from the enemies. It looks like they drop up to 5 each, but you could achieve the same thing by making them only drop 1 piece that gives more xp. Also, make the magnetized speed faster than the player because outrunning the drops seemed to cause most of the lag.
Anyways, keep me posted if you ever update this - it's a lot of fun :]