User experience designers Alex Faaborg and Alexander Limi are looking to broaden the scope of efforts to make Firefox faster. Until recently, most of the effort has involved reducing the computation time needed to launch Firefox or render a web page. Faaborg and Limi argue that we should also look for ways to make computation time matter less.
The wiki page Perceived Performance contains a long list of ideas. Don't be fooled by the "perceived" part of the name: although a few of the ideas would merely make Firefox users happier, most of the ideas are aimed at reducing the amount of time users spend waiting for Firefox to do various things.
Common themes include:
Improve handling and feel during input. For example, letting scrolling "accelerate" makes rapid scrolling easier without harming the ability to make fine adjustments.
Give instant feedback in response to input, even if an operation has to continue in the background. In addition to reducing human waiting time, these fixes make the experience feel more like direct manipulation and less like telling Firefox what to do. (See also: "snappiness" bugs.)
Allow users to interact with partially loaded pages sooner. This is especially important with slow connections, which are becoming common again as computing goes mobile. Boris Zbarsky's interruptible reflow work is likely to help, and I added some ideas about making better use of the cache.
Reduce the number of clicks and keypresses needed for the most common interactions.
Give users new tools that let them avoid waiting. The introduction of tabbed browsing made it matter less when pages loaded slowly, by letting users load links in background tabs while continuing to read, but also introduced new problems.
Diminish frustration when slowness can't be helped by making changes to activity indicators, progress bars, and other messages. Give users the impression that Firefox is working hard, and help users make better choices about whether to wait.
What kinds of slowness do you encounter while using Firefox? Where should we focus performance efforts, whether by reducing computation time or through more clever means? Can you think of new ways to apply the themes above, or any other ways to make Firefox faster where it matters?