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Yahoo's YSlow Plug-in Tells You Why Your Site is Slow
Stoyan writes "Steve Souders, performance architect at Yahoo, announced today the public release of YSlow — a Firefox extension that adds a new panel to Firebug and reports page's performance score in addition to other performance-related features. Here is a review plus helpful tips how to make the scoring system match your needs.
that's all well and good, but it's slow because of the server-side scripts, not anything client side. and no browser plugin will ever know that.
Nice one Yahoo. Now people can optimize their website without bothering to read up on HTTP and thinking about what they're doing.
Since 9/10 web developers can't even be bothered using a validator, I predict great success for this tool.
I see your point, but keep in mind that the website server iikely has a far better uplink to the Internet than you do. A plug-in like this gives you real-world performance data if you're using it on, say, a residential DSL line.
Interesting approach, with lots of flaws.
For example "use CDN" (aka Akamai, etc.) - yeah, right. For Yahoo.com that's an idea. For my private website, that's bullshit. If they really use this internally to rate sites, their rating sucks by definition.
So in summary there are a couple good points there, and a couple that are not really appropriate. Expires: Headers are a nice idea for static webpages. But YSlow still gives me an F for not using one on a PHP page that really does change every time you load it.
Assorted stuff I do sometimes: Lemuria.org
Yeah it says the same for Slashdot's css files, which are indeed in the head. Guess that's a YSlow bug.
The Anonymous Coward here is spot on. This thing gives awful, awful advice. Some of these in particular I really hated as a dialup user.
This is only a win if your images are tiny. Why are you optimizing for this? Tiny images do not take long to download, even on dialup, because they are tiny. Frankly I would prefer to have all the site's little icons progressively appear as they become available than have to wait while a single image thirty times the size of any one of them loads. Or, perhaps, fails to load, so that I have to download the whole thing again instead of just the parts I have.
This is hands down the stupidest idea I have ever heard. Ignoring for the moment that it won't even work for the 70% of your visitors using IE, sending the same image multiple times as base64-encoded text will completely swamp any overhead that would have been introduced by the HTTP headers.
Less egregious than suggesting CSS Sprites, but it still suffers from the same problems. These are not large files, and if they are large files, the headers are not larger.
What, seriously? Are you really optimizing for your visitors who load one and only one page before their cache is cleared? Even though you "measured... and found the number of page views with a primed cache is 75-85%"?
And if you ever change something but forget to change the file name, your visitors will have to reload everything on the damn page to get the current version of the one thing you changed. Assuming, of course, they even realize there should be a newer version than the one they're seeing. And assuming that they actually know how to do that.
Um. Duh? link elements are not valid in the body. style elements are
Terrorists can't threaten a country's freedom and democracy. Only lawmakers and voters can do that.
In my experience "slow" is a very subjective measure of a web site. It really depends on how quickly the content is displayed, not how quickly the entire page is loaded and rendered.
Lets say you visit, oh, dilbert.com (just to pick on a geeky site) to get your daily dose of dilbert. If the first thing that is rendered on your screen is the actual comic, you don't really care that it takes another 10-20 seconds to display the buttons, menus, sidebars, topbars, bottombars, animations, ads and ads for ads. It can do that while you chuckle over the comic.
On the other hand, if you have to sit there and drum your fingers while all the other crap loads first before you get to look at todays dilbert, then you are going to be muttering "why is this site so freaking slow?" And if wwww.weselladstoadserversbythebillions.com got it's DNS server taken out by a freak lightning strike, you could be sitting there a while.
Would it be possible to have a plug-in or extension, so that I could right click on the actual content of a site and say "next time I visit here, load this bit first?" Yes, I could just block everything else on the site, but then they'll change it a week later, and some of the non-content stuff might actually be useful on occasion. I don't want to have to be in an arms race with a million web-monkeys on a thousand different sites just to browse my RDA of surfing.