Comments on: Yahoo! Announces YSlow, Firebug based performance tool

By: efattal

efattal — Wed, 05 Sep 2007 14:55:02 +0000

Concerning the “tricky” Rule #5: it looks like the CSS files paths have to be LOWER CASE. Too weird!! Now, I have my B score and my life looks much more beautiful :-)

By: Harry Bailey

Harry Bailey — Sat, 28 Jul 2007 03:37:06 +0000

“I could go through the list of 13 myself, and figure out what Iâ€™m failing at without the tool to tell me. Is there something Iâ€™m missing?”

Well, I could take out a fine-tipped pen and a magnifying glass and draw tiny dots on a piece of paper, but instead I have this thing called a printer. At first I didn’t get it, realizing I could just do it myself, but then the convenience, speed, and accuracy won me over.

By: Gaz Elms

Gaz Elms — Fri, 27 Jul 2007 14:02:35 +0000

I think it’s funny that Yahoo of all people have developed a method of rating your site’s slowness.

The new Yahoo Mail isn’t the future of web mail, it’s too slow. In fact it’s so slow I sometimes forget that the future is actually going to happen

By: Mandy

Mandy — Fri, 27 Jul 2007 09:40:12 +0000

You can configure CDN by typing about:config in the url bar in firefox and then do a right click, select New -> String. Type extensions.firebug.yslow.cdnHostnames as preference name and in the value just dump your domain eg ajaxian.com and then you can run your tests again. Actually, a cheap way to escape the ratings for CDN :)

By: nblade

nblade — Thu, 26 Jul 2007 19:41:57 +0000

I have to also say the CDN thing is a bit overweighted. It would be interesting to know how each one is weighted, as I doubt they are equally weighted. It does look like @import in stylesheets tend to confuse it somewhat. I’d like to know exactly how it does that measurement, so that could be explained. I do agree that I’m not sure of the value of this tool. While its fun to look, the values it produces are somewhat misleading and sometimes beyond the control of the developer.

By: Peter Mularien

Peter Mularien — Thu, 26 Jul 2007 17:34:45 +0000

It’s really nice to see a vendor extending Firebug, and not to be a “hater”, but I have to say that I really don’t see the value in this tool. I could go through the list of 13 myself, and figure out what I’m failing at without the tool to tell me. Is there something I’m missing?

I will say the one valuable feature that is kind of buried is the JSLint integration – that is really nice!

By: eugene

eugene — Thu, 26 Jul 2007 11:17:33 +0000

wow, not too sure about how much weight is given to CDN, Expires Header and GZip

i see CDN as an issue if clients ever get a hand on this tool
and can only image the conversations, we got an F on CDN… …we want an A… ….insert $$$ here

B 1. Make fewer HTTP requests
F 2. Use a CDN
F 3. Add an Expires header
F 4. Gzip components
A 5. Put CSS at the top
A 6. Move scripts to the bottom
A 7. Avoid CSS expressions
n/a 8. Make JS and CSS external
A 9. Reduce DNS lookups
A 10. Minify JS
A 11. Avoid redirects
A 12. Remove duplicate scripts
F 13. Configure ETags

By: Morgan Roderick

Morgan Roderick — Thu, 26 Jul 2007 09:25:24 +0000

I see that Yahoo / Chris Heilmann still have not abandoned his ideas of actually adding javascript to THE CONTENT of a page, and adding a the bottom. I’ve already flamed him once for this, and still firmly believe this to be a bad practice.

Yahoo, and Chris, do some exceptional work, but please beware something that says “best practices”… wonderful tool, but don’t replace your brain with it :P

By: Ben

Ben — Thu, 26 Jul 2007 08:41:27 +0000

GMail gets an A (98).

On the subject of CDNs, while there are free services out there this is still a bit of a stretch for most applications. I hope the rules are weighted, and that the CDN rule has less of an impact on the final grade than a rule such as 10 (JS minification).

By: Sergej Andrejev

Sergej Andrejev — Thu, 26 Jul 2007 06:22:01 +0000

It is also completely unsuitable for full size web applications.

Got 32 for mine. I won’t argue that it is slow and it will never be as fast as plain web pages, but when you compare it to all the refreshes you would have to do when not using AJAX you would see that the advantage is on side of non-static pages.

I suggest adding few modes to YSlow indicating what sort of page is this and apply different rules for web applications comparing to web sites.

By: Dave

Dave — Thu, 26 Jul 2007 05:31:41 +0000

Don’t feel bad about bad marks. Yahoo’s YSlow description page gets a D. ;)

By: Alan Doucette

Alan Doucette — Thu, 26 Jul 2007 03:48:55 +0000

Really nice idea. The rules are obviously a little on the idealistic side. Even the YSlow page (http://developer.yahoo.com/yslow/) gets a 67 D.

By: Matt

Matt — Wed, 25 Jul 2007 22:06:00 +0000

Jonathan, I’m getting the same thing where it says my stylesheets are not in the HEAD. I’m getting a D for that.

By: DarkRat

DarkRat — Wed, 25 Jul 2007 20:23:19 +0000

Got 2 D’s :( not my mommy will punish me :(

By: Jonathan Leech

Jonathan Leech — Wed, 25 Jul 2007 19:42:50 +0000

It always gives me a ‘C’ for rule #5.
2 external stylesheets were found outside the document HEAD.
However, I only use one .css, which is in the head. It @imports another .css which might be confusing yslow.

By: Steve Souders

Steve Souders — Wed, 25 Jul 2007 18:21:19 +0000

Thanks for the feedback. I’ve already gotten a lot (scores) of emails about Rule 2 – use a CDN. You can expand and customize the CDN hostnames as described in this FAQ:
http://developer.yahoo.com/yslow/faq.html#faq_cdn

We’ll keep adding to the list of recognized CDNs. If you can’t afford a for-profit CDN service, investigate free services such as Globule, CoDeeN, and CoralCDN.

By: Cory Collier

Cory Collier — Wed, 25 Jul 2007 18:13:01 +0000

The one thing that really stands out about this, is the consistant poor grade most people will get for not utilizing CDN. It’s fair to say that all but a handful of sites are on a single server, or at least a single IP address. Distributing servers across the planet is best left for the largest of sites.

So why penalize people for something that they will most likely not be able to do??

By: Mark Holton

Mark Holton — Wed, 25 Jul 2007 18:04:19 +0000

…this is freakin awesome… so are the 13 rules. Thanks, guys!!!

By: boodie

boodie — Wed, 25 Jul 2007 18:00:52 +0000

That think kicks ass, but doesn’t seem to be too consistent.

Some feedback shows up as: Move JS to bottom, but on sites with JS on bottom it doesn’t say that. Thought I’d get an A for that line item :-)

I got 3 Fs, 1 D and a C. Guess I have some work tado, yet ebay, microsoft and amazon all get a big Fat F as well.

By: Guillermo

Guillermo — Wed, 25 Jul 2007 17:34:56 +0000

Dammit, I got an F! :P