From time to time I access my work emails through Outlook Web Access (OWA) – which works really great on all browsers I run on my laptop (IE, FF, Chrome). Guessing that Microsoft probably optimized OWA for its own browser I thought that I will definitely find JavaScript code that doesn’t execute that well on Firefox as compared to Internet Explorer. From an end users perspective there seems to be no noticeable performance difference – but – using browser diagnostics tools I found a very interesting JavaScript method that shows a big performance difference when iterating over DOM elements.

Read the full blog post that shows how Microsoft leverages the fact that IE supports multiple DOM elements with the same UNIQUE ID.