Google's Chrome browser has an amazing array of built in tools that allow us to both find problems in our websites and allow us to improve, all for free. This talk is for all front end developers working in JavaScript and/or CSS. I will show how to spot performance issues, find memory leaks and how to fix them both. And best of all I will present some easy to remember rules of thumb to prevent these issues from re-occurring.

1. Chrome Dev Tools
How to ImproveYour Site’s Performance

2. Android Wear Talk
• Smart watches are hot!
• Google is getting into the game
• Get ahead of the curve
• Free talk April 24th in LA
• http://bit.ly/1g6RMf6

3. Beginning Android
Class
• Saturday, May 10th & 17th
• From installing the SDKs…
• to deploy to the Play Store
• Learn pro development tips and techniques
• http://bit.ly/1kqsqjP

4. Our Agenda
• The three pillars of page performance
• The Chrome Dev Tools
• Network tools
• Performance tools
• Rendering tools

5. The Three Pillars of Page
Performance
• Network - Connection Speed + Latency
• Compute - JavaScript
• Render - Layout + Paint

6. GradeYour Site
• Google’s PageSpeed Insights
• https://developers.google.com/speed/
pagespeed/insights
• Yahoo’sYSlow
• https://developer.yahoo.com/yslow/

7. PageSpeed Insights
Demo

8. Chrome Dev Tools
• Elements
• Network
• Sources
• Timeline
• Profiles
• Resources
• Audits
• Console

9. Chrome Dev Tools
• Elements
• Network
• Sources
• Timeline

10. Network Panel
• Shows how long it takes for your site to
download
• latency - server processing time
• DOMContentLoaded - The whole
document has been loaded
• load - The document and its resources are
loaded

11. Images
• For most sites, images are the biggest
resource and the easiest win
• Be sure to use the right image type
• Be sure to use the right image size
• Use sprite maps instead individual images

12. Image Types
• JPG - is for photos
• Can usually get good quality down to
75%
• PNG - is for images
• Be sure to pngcrush or other
compression utility

13. Not Using
Compression?
• In one case we scaled a 640x480 image
down to 147x110
• This is 18 times more data than it should
be

14. Yahoo! Smush It Demo

15. Performance Tools

16. Users don't care if an app is desktop or
browser based, they want it to be buttery-
smooth. Buttery-smooth is the opposite of
janky. It is defined as 60 frames a second, or
16.6 ms per frame

17. Performance Tools
• The performance tools measure the
amount of time it takes to render
• It can also tell you frames per second
• And even potential issues

18. Performance Tool
Demo #1

19. Rendering Options
• Show paint rectangles
• Show composite layer borders
• Show FPS meter
• Enable continuous page repainting
• Show potential scroll bottlenecks

20. Show Paint Rectangles
• Shows the area of the screen being
repainted
• Watch rectangles, the paint will union small
rectangles together

21. Show composite layer
borders
• Layering is a bit complicated
• Layering requires CSS3
• It uses CSS Transform
• Not 100% kosher

22. Show FPS meter
• Running clock of the FPS
• And your min and max frame rate
• Graph of your sites performance

23. Enable continuous page
repainting
• Repaints continuously to show problems
• Best when used with Show Paint Rects.

24. Show potential scroll
bottlenecks
• Scrolling is a place for your site to shine
• Turning this feature on shows:
• Events hook up to scroll
• Areas of the page which are repainted

25. Performance Demo #2

26. Resources

27. • Chrome Dev Tools
https://developers.google.com/chrome-
developer-tools/
• Yahoo! Smush It
http://www.smushit.com/ysmush.it/
• PageSpeed Insights
http://developers.google.com/speed/
pagespeed/insights/

28. • PNGCRUSH
http://pmt.sourceforge.net/pngcrush/
• Making Layers
http://aerotwist.com/blog/on-translate3d-
and-layer-creation-hacks/
• How Browsers Work
http://www.html5rocks.com/en/tutorials/
internals/howbrowserswork/