To improve performance, clear your browser's cache and cookies.
Close and reopen your browser.
If your game is still not working, please restart your computer and try to load the game again.
If your game still doesn't work after all these steps, you may have disabled hardware acceleration in your browser settings. Please navigate to your browser settings (in Firefox, this is called "Options").
Hit advanced settings.
Tick the box next to "Use hardware acceleration when available".
Restart the browser for the change to take effect.