On both Firefox and Chrome, my computer has almost completely frozen up while I was playing this game. It happens after maybe an hour or so of playing. It fixes itself if I manage to close the tab the game is in quickly enough. I think there's some kind of memory leak?
A memory leak is a bug that can occur in software. A game can ask the computer for memory–but after it's done using the memory, it's supposed to return all of it to the computer. A memory leak happens when the game fails to return some amount of memory to the computer. Over time, the game asks for more and more memory and never gives it back, so it "leaks" from the computer to the game