Skip to Main Content
High Performance Web Sites
book

High Performance Web Sites

by Steve Souders
September 2007
Intermediate to advanced content levelIntermediate to advanced
170 pages
4h 24m
English
O'Reilly Media, Inc.
Content preview from High Performance Web Sites

YouTube

Figure 17-25. http://www.youtube.com

YouTube's home page (http://www.youtube.com) isn't very heavy, but it has a low YSlow grade and ends up in the bottom half of response times. Figure 17-26 shows that there isn't very much parallelization at the beginning and end. Increasing the level of parallelization in these areas would make the greatest improvement to response times.

YouTube HTTP requests

Figure 17-26. YouTube HTTP requests

In the beginning of the page load, the main hurdle to parallelization is the six scripts downloaded back-to-back. As explained in Chapter 8, scripts block all other downloads, no matter what their hostnames are. Additionally, the scripts aren't minified. Combining these six scripts into a single script and minifying them would decrease the download time. Also, if any of these scripts could be downloaded later in the page, the initial part of the page would be downloaded and rendered sooner.

At the end of the page, decreased parallelization results from downloading 15 images from a single hostname (img.youtube.com). YouTube only uses four unique hostnames in their page. It would be worth the cost of an extra DNS lookup to split these 15 downloads across two hostnames and double the amount of simultaneous downloads.

Sadly, not a single component has a far future Expires header ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Even Faster Web Sites

Even Faster Web Sites

Steve Souders
Back-end Performance

Back-end Performance

Bruno Skvorc, Christopher Pitt, Tonino Jankov, Reza Lavaryan, Daniel Berman

Publisher Resources

ISBN: 9780596529307Errata Page