I occasionally get invited to do JavaScript/AJAX Performance Workshops. Last week I spent two days with a group of dynaTrace AJAX Users that work in a performance task force group within their R&D Organization. I asked them about the reasons for this Client-Side Performance Initiative. They told me the following story:

One of our sales managers started to complain about several pages of the product we sell being too slow to demo therefore impacting his ability to pitch and sell the product. We analyzed the page in-house but couldn’t reproduce the same exact behavior. After some back and forth we identified that it was the Skype Add-On for Internet Explorer caused the performance hit on those pages that had a very large DOM with many table rows and many nested divs. This raised the awareness of client side performance and that there is much to learn about how browser work and how the generated HTML impacts JavaScript, Rendering and IE Add-Ons.

If you query for Skype Add On Performance Problem you actually get several hits on blogs that already talk about this problem: MSDN Blog or Softpedia

Read the full story on why those Add-Ons slow you down and how to identify them.