useless, not working Rated 1 out of 5 stars

worst add on

Literally does nothing Rated 1 out of 5 stars

This plugin must have been killed off a while back. It literally does nothing after you install it. There isn't even a button to click to run the plugin.

This user has a previous review of this add-on.

Rated 1 out of 5 stars

Stopped working.

Furthermore, it will need to be moved into Firefox DevTools instead of Firebug

Not working in FF50 Rated 1 out of 5 stars

Its not working in firefox 50.

Wastage of Time Rated 1 out of 5 stars

stupid add-on. does not install.

does not work Rated 1 out of 5 stars

does not work in v51 nightly.

Do`nt work in FF48 Rated 1 out of 5 stars

Do`nt work in FF48

Everything working FF 48.0 Rated 5 out of 5 stars

Enter this url in FF about:addons.
Then click on YSlow Prefencies and check first checkbox. Then, when u'll reload u page, it would work!

Not working Rated 1 out of 5 stars

In FF 47

Worst Experience Ever Rated 1 out of 5 stars

This addon is a total waste of time. Not only is this useless because when you finally get to access it - clicking on the "Run Test" doesnt respond, it also irritates you while installing it and figuring out where to find it - ie, inside firebug!

Complete and Utter waste of time ever.

Dead Rated 1 out of 5 stars

This used to be a great addon but has not worked in a very long time. Mozilla should just pull it off the site already.

Does not work Rated 1 out of 5 stars

with Firefox 47

Does not work Rated 1 out of 5 stars

with Firefox 46.

Does not work Rated 1 out of 5 stars

FF 46.0.1

It mostly works for me in FF 46.02! Rated 4 out of 5 stars

In Firefox, go to Add-ons, then Extensions, then see Yslow. Click options and click "Automatically run YSlow when page finishes loading." It will give the overall rating plus the element ratings, but the elements themselves are still not clickable. Great insight anyway.

Not Working Rated 4 out of 5 stars

FF 45 - Yslow was broken

It dosen't work Rated 1 out of 5 stars

there isn't anything work,click yslow there isn't anything happen

Not working Rated 1 out of 5 stars

Installed for Firefox 44.0.2 - doesn't run.

Broken Rated 1 out of 5 stars

Used to work great, but seems to be broken.

YSlow Workaround! Rated 1 out of 5 stars

It's clear from this very long thread YSlow isn't working anymore with current FF versions. However there's hope!

These three sites will give the web page speed info desired and more: gtmetrix.com | host-tracker.com | webpagetest.org

gtmetrix.com has both PageSpeed and YSlow operating.