Chrome Dev ToolsHow to Improve Your Site’s Performance

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

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

Our Agenda

• The three pillars of page performance

• The Chrome Dev Tools

• Network tools

• Performance tools

• Rendering tools

The Three Pillars of Page Performance

• Network - Connection Speed + Latency

• Compute - JavaScript

• Render - Layout + Paint

Grade Your Site

• Google’s PageSpeed Insights

• https://developers.google.com/speed/pagespeed/insights

• Yahoo’s YSlow

• https://developer.yahoo.com/yslow/

PageSpeed Insights Demo

Chrome Dev Tools• Elements

• Network

• Sources

• Timeline

• Profiles

• Resources

• Audits

• Console

Chrome Dev Tools

• Elements

• Network

• Sources

• Timeline

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

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

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

Not Using Compression?

• In one case we scaled a 640x480 image down to 147x110

• This is 18 times more data than it should be

Yahoo! Smush It Demo

Performance Tools

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

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

Performance Tool Demo #1

Rendering Options

• Show paint rectangles

• Show composite layer borders

• Show FPS meter

• Enable continuous page repainting

• Show potential scroll bottlenecks

Show Paint Rectangles

• Shows the area of the screen being repainted

• Watch rectangles, the paint will union small rectangles together

Show composite layer borders

• Layering is a bit complicated

• Layering requires CSS3

• It uses CSS Transform

• Not 100% kosher

Show FPS meter

• Running clock of the FPS

• And your min and max frame rate

• Graph of your sites performance

Enable continuous page repainting

• Repaints continuously to show problems

• Best when used with Show Paint Rects.

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

Performance Demo #2

Resources

• Chrome Dev Toolshttps://developers.google.com/chrome-developer-tools/

• Yahoo! Smush Ithttp://www.smushit.com/ysmush.it/

• PageSpeed Insightshttp://developers.google.com/speed/pagespeed/insights/

• PNGCRUSH http://pmt.sourceforge.net/pngcrush/

• Making Layershttp://aerotwist.com/blog/on-translate3d-and-layer-creation-hacks/

• How Browsers Work http://www.html5rocks.com/en/tutorials/internals/howbrowserswork/