What type of device are you playing on, and which web browser? I tested on a Steam Deck (so fairly low-end) and got 60 fps at 1080p (the vsync cap, so it likely gets more) on Chrome and 40fps at 1080p on Firefox.
Ok, was able to publish a Windows build. Because I didn't want to alter the code at all, there's no way to quit to desktop, therefore I have it default to 720p windowed mode to play it safe.