This post is
one in a series that previews Google I/O, our biggest
developer event in San Francisco, May 28-29. Over the next month, we'll be highlighting
sessions and speakers to give Google Code Blog readers a better sense of what's in store for
you at the event. - Ed.
In April I announced
that I'm starting another book. The working title is High Performance Web Sites, Part
2. This book contains the next set of web performance best practices that goes
beyond my first book and YSlow. Here are the rules I have so
far:
Split the initial payload
Load scripts
without blocking
Don't scatter scripts
Split dominant
content domains
Make static content cookie-free
Reduce
cookie weight
Minify CSS
Optimize
images
Use iframes sparingly
To www or not to
www
I'm most excited about the best practices for improving JavaScript
performance (rules 1-3). Web sites that are serious about performance are making progress on
the first set of
rules, but there's still a lot of room for improving JavaScript performance. Across
the ten top U.S. sites approximately 40% of the time to load the page is spent downloading and
executing JavaScript, and only 26% of the JavaScript functionality downloaded is used before
the onload event.
In my session at Google I/O I'll present the research
behind rules 1-3, talk about how the ten top U.S. web sites perform, demonstrate Cuzillion, and give several takeaways
that you can use to make your web site faster.
