Ajax Performance Analysis

IBM Developerworks' latest was submitted to us by an anonymous reader who writes "Using Firebug and YSlow, you can thoroughly analyze your Web applications to make educated changes to improve performance. This article reviews the latest tools and techniques for managing the performance of Ajax applications along the life cycle of your application, from inception through production."

Comments

A capacity planner's niggle

[davecb]

It's actually useful to break the response time out into three parts:

1. 1) Round-trip time, the latency from the network

   2) Transfer time, the time from receiving the first byte of the page to the time the last byte arrives. This varies greatly with page size, and is the time you use to do KB/S calculations as well.

2. 3) Latency proper, the time between sending the request and receiving the first byte of the page. This is the time that grows during an overload, and the one that capacity planners use to do queuing models to see how much the server will slow down by under an overload.

--dave (a capcity planner) c-b

Take Firebug with a grain of salt

[TLLOTS]

While I love Firebug and use it daily for web development, you shouldn't trust its net tab too much. I've found in numerous instances it has grossly understated load times, for example loading a very PHP heavy page which Firebug claimed was loading in 13ms, however serverside performance testing showed that the load time was actually over 1 second. I've actually found Safari's new Web Inspector tools to be much more accurate in this regard so I'd recommend using them for performance testing if you suspect Firebug isn't telling you everything.

Re:NoScript

[Anonymous Coward]

I concur. This is all the more reason to use unobtrusive JavaScript. Same great functionality with more compatibility. I just wish more sights would learn how this works.