Ajax application performance largely depends on the performance of JavaScript execution and browser DOM operations. I've heard various people saying various things about Ajax performance. Some people say JavaScript is just too slow. Some people say that the problem is not JavaScript but rather Browser DOM being too slow. Some people would then argue that browser DOM operations are fine. The problem is Internet Explorer that is unbelievably slow.

What is the reality? Having heard enough but haven’t seen enough data to clearly justify one argument against the other ones, I decided to take some time and do some study in this area.