Hi,
" There is also a lot of potential for optimisations in the basic code. " <=== Good.
"but this information helps me to judge how much effort to spend making it playable on slower machines." <=== Good.
I notice that Matrix Defense wins the 6th place. Quite good. There are so many jams on Itch.io. I believe that your game development skills will be very excellent after you participate in different types of game jams on Itch.io.