Stubbornella - Nicole Sullivan

I’ve been tweeting and posting to delicious about reflows and repaints, and it seemed time for a blog post. Opera lists repaint and reflow as one of the three main contributors to sluggish JavaScript, so it definitely seems worth a look.

Reflows are very expensive in terms of performance, and is one of the main causes of slow DOM scripts, especially on devices with low processing power, such as phones. In many cases, they are equivalent to laying out the entire page again.

How to avoid reflows or at least minimize their impact on performance?

1. Change classes on the element you wish to style (as low in the dom tree as possible)
2. Avoid setting multiple inline styles
3. Apply animations to elements that are position fixed or absolute
4. Trade smoothness for speed
5. Avoid tables for layout
6. Avoid JavaScript expressions in the CSS (IE only)

Tools

A few tools have made waves lately. Stoyan Stefanov and I have been looking for decent ways to measure reflows and repaints and there are a few tools which show promise (despite being very early alpha).

• UPDATE: Lindsey Simon at Google wrote a bookmarklet that tests reflow times on any browser. Fantastic. (Note: all that shaking is normal!)
• John Resig wrote a bookmarklet to visualize paint events.
• Kyle Scholz created this tool to visualize paint events before onload.
• Alex at Yoono has created the XUL profiler.

Has anyone else seen any cool tools for evaluating reflows?

My Object Oriented CSS grids and templates are open sourced on github. They have all the functionality of YUI grids plus some important features.

• Only 4kb, half the size of YUI grids. (I was totally happy when I checked the final size!)
• They allow infinite nesting and stacking.
• The only change required to use any of the objects is to place it in the HTML, there are no changes to other places in the DOM and no location dependent styling. Eases back-end development and makes it a lot easier to manage for newbies.
• Solution for sub-pixel rounding errors.

http://wiki.github.com/stubbornella/oocss

template.css and grids.css

…My prediction is that you’ll be writing complex layouts in less than 24 hours without adding a line to the CSS file.

Je vais parler (en francais! eek!) avec Eric Daspet de la performance des images pour le web a ParisWeb. Les inscriptions pour Paris Web 2008 sont officiellement ouvertes. Jusqu’au 15 octobre au soir, vous bénéficierez de tarifs réduits. Le conference sera lieu a Paris le 13-15 Novembre. J’attend vous voir bientot alors.

Voila le proposition

Voulez-vous améliorer la vitesse de vos pages web et réduire l’impact écologique et monétaire de votre hébergement ? Voulez-vous faire ceci avec peu de changement de code et en gardant une belle interface graphique ? Cette session va vous apprendre les 7 étapes pour mettre votre site web au régime. Comment perdre des poids que votre site a pris en rajoutant les dernières nouveautés. Et, encore plus important, comment ne pas reprendre ce poids !

The YUI team released YUI3 for a sneak peek preview. The goals make me happy… especially goal 2.

1. lighter (less K-weight on the wire and on the page for most uses)
2. faster (fewer http requests, less code to write and compile, more efficient code)
3. more consistent (common naming, event signatures, and widget APIs throughout the library)
4. more powerful (do more with less implementation code)
5. more securable (safer and easier to expose to multiple developers working in the same environment; easier to run under systems like Caja or ADsafe)

Well, not quite. But I am pleased with the results. Who would have thought that the shy girl who almost failed a public speaking course at university would turn out to really enjoy presenting. Turns out I only like speaking about geeky things, preferably to geeks. A limitation perhaps, but far less limiting than nearly peeing myself with fear in college. No, not literally.

Anyway, check it out. It is jam packed with brand new performance ideas to make your site fly.

The Exceptional Performance team at Yahoo! added 20 new performance rules and refined some of the original rules. I’m really excited about this; this performance goodness is just what developers need to accelerate the user experience even further.

1. Flush the buffer early
2. Use GET for AJAX requests
3. Post-load components
4. Preload components
5. Reduce the number of DOM elements
6. Split components across domains
7. Minimize the number of iframes
8. No 404s
9. Reduce cookie size
10. Use cookie-free domains for components
11. Minimize DOM access
12. Develop smart event handlers
13. Choose <link> over @import
14. Avoid filters
15. Optimize images
16. Optimize CSS sprites
17. Don’t scale images in HTML
18. Make favicon.ico small and cacheable
19. Keep components under 25K [mobile]
20. Pack components into a multipart document

Stay tuned, we’ve got more tricks up our sleeve.