Inspired by the Top 10 Performance Problems post which focuses on Server-Side performance problems taken from companies such as Zappos, Thomson, Monster and Novell I came up with the Top 10 Client-Side performance problems in Web 2.0 applications I’ve seen when working with our dynaTrace AJAX Edition users.

Symptom: JavaScript blocking resource downloads and slowing page load time

JavaScript opened the door for Web 2.0 applications. Since JavaScript is used on almost every web site traditional methods to analyze web site performance don’t always give you all the answers for a slow running page. Looking at a network waterfall diagram is the typical way to start analyzing a page and all its requests. Most browser performance tools support a network waterfall diagram. It shows which resources got downloaded and how much time the browser had to wait for all these resources to be downloaded. Tools such as dynaTrace AJAX Edition or Google Speed Tracer allow analyzing these blank spots that block further network downloads as they analyze JavaScript execution, DOM access and Rendering activity in the browser while loading a page. Long running JavaScript executed when JavaScript files are loaded cause the browser to suspend download of remaining network resources and therefore slows down the overall page load time.

Top 10 Problems that explain these symptoms

continue at Top 10 Client-Side performance problems in Web 2.0 applications