Analyzing Client-side Performance Issue with YSlow
Posted: January 4th, 2010 | Author: TnT Admin | Filed under: Tools | Tags: Add-Ons, Analyze, Bottleneck, firefox | No Comments »
YSlow, another popular client-side performance profiling tool for web applications, is an add-on for Firefox. With YSlow, you will be able to determine how fast (or slow) your web page is loading, breaking down to the individual components on the web page. One thing to note, YSlow requires another add-on, Firebug to be installed in Firefox before you can install it. With YSlow you can use to determine the following website performance problems:
- Download Component Size – YSlow provides the size of the downloaded component and provides suggestion in keeping the optimum amount of data size that the component should be. This include images, Javascripts, CSS and cookie size are just few of the examples.
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YSlow Screenshot
Bad Requests – It detects missing components that churns 404 errors. Addressing 404 errors can help improve performance at the client and server end by removing requests made on missing objects as well as removing time needed to handle this requests on missing objects on the server.
- Detect duplicate requests/components – It detects duplicate HTTP requests made which degrades both the client and the server performance. It also detects duplicate Javascripts which can result in duplicate request to the server or further slowing down the client browser.
- Placement of files – Another good feature made by YSlow is the detection of the placement of the Javascripts and CSS files. The placement of the Javascripts and CSS files will help improve the performance at the client side.
- Detect expiry of components – YSlow can help determine if a component should be retrieved on every web page loading. If a component such as an image (company banner) does not changed frequently, it is suggested to it expire at a far later date. Else, for every time the page loads, a request will be made to the image.
What is great about YSlow is it provides you with the best practises for creating high performance web sites. It helps you detect which components are too big and provide suggestions for you to improve the performance. The best practises for high performance web sites can be found at Yahoo! YSlow Developer Network.
The disadvantage of YSlow is it is not installable on Internet Explorer, unlike HTTPWatch. If you are a fan of the real-time analysing the response (wait) time on HTTPWatch, then you will be disappointed with YSlow on this. YSlow does not provide any visual indicator on the time taken during loading (or requesting to the server) in real time. It will only display the time only after the entire web page is downloaded.
The above are just some of the features that are available in YSlow. You can download YSlow and start profiling your website. We hope to hear your review soon!