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High Performance Web Sites
Want your web site to display more quickly? This book
presents 14 specific rules that will cut 25% to 50% off
response time when users request a page. Author Steve
Souders, in his job as Chief Performance Yahoo!, collected
these best practices while optimizing some of the
most-visited pages on the Web. Even sites that had already
been
highly optimized, such as Yahoo! Search and the Yahoo!
Front Page, were able to benefit from these surprisingly
simple performance guidelines.
The rules in High Performance Web Sites explain how you can
optimize the performance of the Ajax, CSS, JavaScript,
Flash, and images that you've already built into your site
-- adjustments that are critical for any rich web
application. Other sources of information pay a lot of
attention to tuning web servers, databases, and hardware,
but the bulk of display time is taken up on the browser side
and by the communication between server and browser. High
Performance Web Sites covers every aspect of that process.
Each performance rule is supported by specific examples, and
code snippets are available on the book's companion web
site. The rules include how to:
Make Fewer HTTP Requests
Use a Content Delivery Network
Add an Expires Header
Gzip Components
Put Stylesheets at the Top
Put Scripts at the Bottom
Avoid CSS Expressions
Make JavaScript and CSS External
Reduce DNS Lookups
Minify JavaScript
Avoid Redirects
Remove Duplicates Scripts
Configure ETags
Make Ajax Cacheable
If you're building pages for high traffic destinations and
want to optimize the experience of users visiting your site,
this book is indispensable.
"If everyone would implement just 20% of Steve's guidelines,
the Web would be a
dramatically better place. Between this book and Steve's
YSlow extension, there's really
no excuse for having a sluggish web site anymore."
-Joe Hewitt, Developer of Firebug debugger and Mozilla's DOM
Inspector
"Steve Souders has done a fantastic job of distilling a
massive, semi-arcane art down to a set of concise,
actionable, pragmatic engineering steps that will change the
world of web performance."
-Eric Lawrence, Developer of the Fiddler Web Debugger,
Microsoft Corporation
CONTENTS:
Foreword
Preface
A. The Importance of Frontend Performance
Tracking Web Page Performance
Where Does the Time Go?
The Performance Golden Rule
B. HTTP Overview
Compression
Conditional GET Requests
Expires
Keep-Alive
There's More
1. Rule 1: Make Fewer HTTP Requests
Image Maps
CSS Sprites
Inline Images
Combined Scripts and Stylesheets
Conclusion
2. Rule 2: Use a Content Delivery Network
Content Delivery Networks
The Savings
3. Rule 3: Add an Expires Header
Expires Header
Max-Age and mod_expires
Empty Cache vs. Primed Cache
More Than Just Images
Revving Filenames
Examples
4. Rule 4: Gzip Components
How Compression Works
What to Compress
The Savings
Configuration
Proxy Caching
Edge Cases
Gzip in Action
5. Rule 5: Put Stylesheets at the Top
Progressive Rendering
sleep.cgi
Blank White Screen
Flash of Unstyled Content
What's a Frontend Engineer to Do?
6. Rule 6: Put Scripts at the Bottom
Problems with Scripts
Parallel Downloads
Scripts Block Downloads
Worst Case: Scripts at the Top
Best Case: Scripts at the Bottom
Putting It in Perspective
7. Rule 7: Avoid CSS Expressions
Updating Expressions
Working Around the Problem
Conclusion
8. Rule 8: Make JavaScript and CSS External
Inline vs. External
Typical Results in the Field
Home Pages
The Best of Both Worlds
9. Rule 9: Reduce DNS Lookups
DNS Caching and TTLs
The Browser's Perspective
Reducing DNS Lookups
10. Rule 10: Minify JavaScript
Minification
Obfuscation
The Savings
Examples
Icing on the Cake
11. Rule 11: Avoid Redirects
Types of Redirects
How Redirects Hurt Performance
Alternatives to Redirects
12. Rule 12: Remove Duplicate Scripts
Duplicate Scripts-They Happen
Duplicate Scripts Hurt Performance
Avoiding Duplicate Scripts
13. Rule 13: Configure ETags
What's an ETag?
The Problem with ETags
ETags: Use 'Em or Lose 'Em
ETags in the Real World
14. Rule 14: Make Ajax Cacheable
Web 2.0, DHTML, and Ajax
Asynchronous = Instantaneous?
Optimizing Ajax Requests
Caching Ajax in the Real World
15. Deconstructing 10 Top Sites
Page Weight, Response Time, YSlow Grade
How the Tests Were Done
Amazon
AOL
CNN
eBay
Google
MSN
MySpace
Wikipedia
Yahoo!
YouTube
Index
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