Hey hey, thank you for your detailed feedback! The slowing down of the game is puzzling me, but I will get to the bottom of this! Apart from that, my personal best score was 430 (-ish), so you bested me! Good job :)
I was running it on respectable specs too (ryzen 3600x + RX590). IIRC the slowdown was proportional to the number of cards on the board, I can try to repro that if you want.
