Scierra, the developer of HTML5-based game creation web app Construct 2 revealed in a blog post that Internet Explorer 10 is the slowest browser when it comes to HTML5 gaming. Microsoft's IE10 which is a default browser of Windows 8 lacks many important features and it doesn't support WebGL API, which basically turns it into a much slower browser as compared to its rivals.
He performed a series of tests and revealed that Internet Explorer 10 is 25 times slower than Google Chrome, while Firefox is 8 times faster than IE10.
Source: Scierra