Tilt Visualization and CSS Performance

Facebook City

Today, I’m blogging from the HTML5Dev Conference.  The house is packed, and I’m breaking out of my shell as a tester to have a look at all of this from the dev perspective.  Of course, the tester in me has tagged along.  What’s great about conferences in the age of twitter is that you are never in a bubble during these things.  One of my co-workers, Greg Koberger tweeted about some performance testing win for the lastest Firefox release, Firefox 7.

Greg's tweet

In taking a look at the lifehacker article he tweeted, I noticed that there was a category for css performance tests.  Since I spend all day, every day looking at selenium tests that have css locators and I sit next to a css dev (who has excellent taste in rap), css has been on the brain lately.  “Hmm…css peformance…LET’S GOOGLE.”  If you google for css peformance, the first link is for an article titled, Performance Impact of CSS Selectors, by Steve Souders.  Given, the article is talking about Firefox 3.0 so it’s obviously a bit long in the tooth, but it’s interests me for not one, but two reasons:

  1. I’m waiting for the talk “High Performance HTML5” to begin.  It’s being given by Steve Souders.  (Serendipity or Coincidence?  I shall leave you, dear reader, to ponder.)
  2. The article has a list of different websites and the number of DOM elements in each one.

Since this is a guerilla blog post I’m finishing up as a talk starts, I have no intention of delving deeply into the guts of the article, at the moment.  What I can share, however, is a new Firefox addon I’ve been playing with called Tilt.  The picture you see above is my Facebook page, turned on it’s side in tilt.  Tilt visualizes a web page’s dom elements in 3d and was developed by a Mozilla intern who has recently been hired.  So if we filter the list in the article, Google has the least number of elements while Facebook has the most.  It should be no surprise that the Google home page has had its performance tweaked to oblivion.  Here we can compare the dom of Google visually with the Dom of Face book.


Facebook Tilt



Google tilt


I’m definitely forming a hypothesis about the CSS performance of these two pages based on their tilt results.

And that’s your guerilla blog post from the HTML5Dev  Conf.   They really ought to make this thing 2 days next year.  It’s pretty cool.

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