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.

Pulling my teeth out. And hair. Rated 1 out of 5 stars

Just installed Yslow. I think. Where can I find it? Where can I click on something to see something? I don't understand. There is no status bar so there is no Yslow icon. If I hit F12 I don't see Yslow anywhere. Am I missing something? Do I have to use Chrome from now on, which I don't want?

Broken on purpose. Rated 1 out of 5 stars

To force users to switch from Firefox to Chrome. Seek for alternatives.

Problem Rated 1 out of 5 stars

I just install it but not working correctly . What can i do for this ?????????

Broke Rated 1 out of 5 stars

Broke on latest version

Rated 5 out of 5 stars

this is best but, i am not able to work, please help

Not working Rated 1 out of 5 stars

It dosen't working.

YSlow no longer working Firefox 40.0.3 Rated 1 out of 5 stars

Buttons cannot be clicked. None of them, as far as I can tell. Tried several times just to make sure I wasn't crazy, but yeah, this appears to be bricked.