[Chrome, Firefox, Opera] Find out why a website loads slowly with YSlow

In today’s bigger and faster world, we don’t want a website to load slow. YSlow will tell you if a website is slow and why. This addon is mostly directed to webmasters and hosts rather than the average Joe but it may still be fun to use if you are interested in this type of thing.

What is it and what does it do

Main Functionality

Lets you analyze websites to see what is slowing them down.


  • Fast and easy to use
  • Shows a detailed analysis of what is loading on a page, including JavaScripts, CSS, AJAX, objects, cookies, etc.
  • Ranks page speed based on research-backed and industry-accepted criteria, ranging from number of HTTP requests to DNS lookups to redirects to cookie size and everything in between.
  • Provides recommendations on how to fix issues


  • Only really designed for the web developer/designer, or someone who maintains a website


This addon/extension is a great addition to anyone who does any kind of website design or maintenance. It allows you to see what is slowing down a website. You can also use it to find out what is wrong with your favorite site and maybe weasel your way into some consulting money; however, unless you know what you are talking about I do not recommend that last suggestion.

Overall the checking of the websites was fast and well done. I only had differences between tests once or twice and it turned out to be very good and consistent. In the screenshot above, I am reviewing dotTech’s website. And one of the best parts about this addon/extension is that is is available on four out of five of the major web browsers that people use today, Chrome, Firefox, Opera, and Safari.

Take note that sometimes the results from YSlow are not always the same, even when you run consecutive tests right after each other. This is because web servers may have a different amount of load from second to second, so difference in performance is to be expected as long as it isn’t too drastic. Secondly, as already mentioned multiple times, this is really only for people that maintain websites for a living or who run/own a site. This extension could be fun for the average user, however it would not be really that useful for said user.

One of the many changes that I would make to YSlow is a more graphic user interface. Currently YSlow has too much of a… codey… look to it. However, since this is a more pro tool than for the average user, the “codey” look seems about right even if I don’t like it. I also really wish that the developer would make the versions the same across all devices.

Conclusion and download link

As a person who uses, contributes, and runs many website,s this is a very welcome addition to my arsenal of tools to help make mine and others websites better. Overall YSlow works really well and helped me improve the speed of the websites I maintain. I would recommend this to anyone who wants to get started in web design.

Price: Free

Version reviewed: 3.0.5 (Opera), 3.1.2 (Chrome), 3.1.4 (Firefox), and Safari version unknown

Requires: Safari, Chrome, Firefox, or Opera

YSlow homepage | Firefox addon page | Chrome extension page | Opera addon page

[Disclaimer: For the purposes of this review, this extension was tested on Opera.]

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