Clear your browser's cache and cookies to improve performance.
  1. Close and reopen your browser.
  2. If the game still isn't working, please restart your computer and try to load the game again.
Ensure you haven't disabled hardware acceleration in your browser settings. 
  1. Navigate to your browser settings (in Firefox, this is called "Options").
  2. Click 'Advanced Settings'.
  3. Tick the box next to "Use hardware acceleration when available".
  4. Restart the browser for the changes to take effect.