Credits
　　Preface
　　1. Understanding Ajax Performance
　　 Trade-offs
　　 Principles of Optimization
　　 Ajax
　　 Browser
　　 Wow!
　　 JavaScript
　　 Summary
　　2. Creating Responsive Web Applications
　　 What Is Fast Enough?
　　 Measuring Latency
　　 When Latency Goes Bad
　　 Threading
　　 Ensuring Responsiveness
　　 Web Workers
　　 Gears
　　 Timers
　　 Effects of Memory Use on Response Time
　　 Virtual Memory
　　 Troubleshooting Memory Issues
　　 Summary
　　3. Splitting the Initial Payload
　　 Kitchen Sink
　　 Savings from Splitting
　　 Finding the Split
　　 Undefined Symbols and Race Conditions
　　 Case Study: Google Calendar
　　4. Loading Scripts Without Blocking
　　 Scripts Block
　　 Making Scripts Play Nice
　　 XHR Eval
　　 XHR Injection
　　 Script in Iframe
　　 Script DOM Element
　　 Script Defer
　　 document.write Script Tag
　　 Browser Busy Indicators
　　 Ensuring (or Avoiding) Ordered Execution
　　 Summarizing the Results
　　 And the Winner Is
　　5. Coupling Asynchronous Scripts
　　 Code Example: menu.js
　　 Race Conditions
　　 Preserving Order Asynchronously
　　 Technique 1: Hardcoded Callback
　　 Technique 2: Window Onload
　　 Technique 3: Timer
　　 Technique 4: Script Onload
　　 Technique 5: Degrading Script Tags
　　 Multiple External Scripts
　　 Managed XHR
　　 DOM Element and Doc Write
　　 General Solution
　　 Single Script
　　 Multiple Scripts
　　 Asynchronicity in the Real World
　　 Google Analytics and Dojo
　　 YUI Loader Utility
　　6. Positioning Inline Scripts
　　 Inline Scripts Block
　　 Move Inline Scripts to the Bottom
　　 Initiate Execution Asynchronously
　　 Use Script Defer
　　 Preserving CSS and JavaScript Order
　　 Danger: Stylesheet Followed by Inline Script
　　 Inline Scripts Aren’t Blocked by Most Downloads
　　 Inline Scripts Are Blocked by Stylesheets
　　 This Does Happen
　　7. Writing Efficient JavaScript
　　 Managing Scope
　　 Use Local Variables
　　 Scope Chain Augmentation
　　 Efficient Data Access
　　 Flow Control
　　 Fast Conditionals
　　 Fast Loops
　　 String Optimization
　　 String Concatenation
　　 Trimming Strings
　　 Avoid Long-Running Scripts
　　 Yielding Using Timers
　　 Timer Patterns for Yielding
　　 Summary
　　8. Scaling with Comet
　　 How Comet Works
　　 Transport Techniques
　　 Polling
　　 Long Polling
　　 Forever Frame
　　 XHR Streaming
　　 Future Transports
　　 Cross-Domain
　　 Effects of Implementation on Applications
　　 Managing Connections
　　 Measuring Performance
　　 Protocols
　　 Summary
　　9. Going Beyond Gzipping
　　 Why Does This Matter?
　　 What Causes This?
　　 Quick Review
　　 The Culprit
　　 Examples of Popular Turtle Tappers
　　 How to Help These Users?
　　 Design to Minimize Uncompressed Size
　　 Educate Users
　　 Direct Detection of Gzip Support
　　10. Optimizing Images
　　 Two Steps to Simplify Image Optimization
　　 Image Formats
　　 Background
　　 Characteristics of the Different Formats
　　 More About PNG
　　 Automated Lossless Image Optimization
　　 Crushing PNGs
　　 Stripping JPEG Metadata
　　 Converting GIF to PNG
　　 Optimizing GIF Animations
　　 Smush.it
　　 Progressive JPEGs for Large Images
　　 Alpha Transparency: Avoid AlphaImageLoader
　　 Effects of Alpha Transparency
　　 AlphaImageLoader
　　 Problems with AlphaImageLoader
　　 Progressively Enhanced PNG8 Alpha Transparency
　　 Optimizing Sprites
　　 ǖber-Sprite Versus Modular Sprite
　　 Highly Optimized CSS Sprites
　　 Other Image Optimizations
　　 Avoid Scaling Images
　　 Crush Generated Images
　　 Favicons
　　 Apple Touch Icon
　　 Summary
　　11. Sharding Dominant Domains
　　 Critical Path
　　 Who’s Sharding?
　　 Downgrading to HTTP/1.0
　　 Rolling Out Sharding
　　 IP Address or Hostname
　　 How Many Domains
　　 How to Split Resources
　　 Newer Browsers
　　12. Flushing the Document Early
　　 Flush the Head
　　 Output Buffering
　　 Chunked Encoding
　　 Flushing and Gzip
　　 Other Intermediaries
　　 Domain Blocking During Flushing
　　 Browsers: The Last Hurdle
　　 Flushing Beyond PHP
　　 The Flush Checklist
　　13. Using Iframes Sparingly
　　 The Most Expensive DOM Element
　　 Iframes Block Onload
　　 Parallel Downloads with Iframes
　　 Script Before Iframe
　　 Stylesheet Before Iframe
　　 Stylesheet After Iframe
　　 Connections per Hostname
　　 Connection Sharing in Iframes
　　 Connection Sharing Across Tabs and Windows
　　 Summarizing the Cost of Iframes
　　14. Simplifying CSS Selectors
　　 Types of Selectors
　　 ID Selectors
　　 Class Selectors
　　 Type Selectors
　　 Adjacent Sibling Selectors
　　 Child Selectors
　　 Descendant Selectors
　　 Universal Selectors
　　 Attribute Selectors
　　 Pseudo-Classes and Pseudo-Elements
　　 The Key to Efficient CSS Selectors
　　 Rightmost First
　　 Writing Efficient CSS Selectors
　　 CSS Selector Performance
　　 Complex Selectors Impact Performance (Sometimes)
　　 CSS Selectors to Avoid
　　 Reflow Time
　　 Measuring CSS Selectors in the Real World
　　Appendix: Performance Tools
　　Index