Help us improve the Perceived Performance of Firefox

There’s a particular type of performance optimization that can have profound differences in the user experience of a product: Perceived Performance.

You are probably aware of the fact that the upcoming release of Firefox 3.5 is the fastest and most memory efficient release of Firefox ever. But did you know that there is a way to help us make it even faster?

The concept of “Perceived Performance” is not as widely known as the classic optimization techniques people usually think about when they try to make their applications faster. But it can make a tremendous difference for the user, and is usually relatively easy to implement once you have identified the area that feels slow.

Now we need your help in locating and coming up with ideas on how to improve this particular aspect of Firefox performance. This is a particularly suitable task for crowdsourcing, as these are things that are hard to discover through measurements, and are all about human perception.

So, what exactly is perceived performance? Let’s illustrate with an existing bug from the Firefox issue tracker, bug 496458:

When restoring a browser session with multiple tabs (especially when restoring 10+ tabs), there’s a feeling of the browser grinding to a halt while the tabs get loaded.

To increase perceived performance and minimize time before you can interact with the first page, we should:

• Load the visible tab (or first + second if this makes more sense) completely before starting on the others.
• If switching to a new tab while this is in process, start loading/rendering that tab too.
• Store the tab titles if possible from the previous session (if we don’t do that already), so it doesn’t feel like there are a bunch of blank tabs while completing the first tab load — even if we haven’t actually started loading them yet.

While this doesn’t actually make anything faster “on paper,” it gives a real-world feeling of the browser being faster and more responsive. You get to the page you were looking at faster, and the others are loaded in the background.

You can help us locate more of these, so we can come up with solutions to them. Which parts of the browser experience makes you feel like you’re waiting needlessly, or make you frustrated?

The best ways to participate are:

• Create a user on the Mozilla wiki, and add it to the list of stuff we should look into on the Perceived Performance page. Make sure you give us some context about what part of Firefox you are referring to when suggesting areas to look at.
• If you are unsure whether something is related to perceived performance, or want to discuss usability and user experience in Firefox in general, you might want to post your thoughts in the Mozilla Usability Google Group — also available in Usenet news group and traditional mailing list flavors.

Oh, and make sure you’re already running Firefox 3.5, so you don’t report performance issues we have already fixed.

Thanks for helping make Firefox even faster!