Improving

web performance

Wed Feb 18 2015

Jhon Jairo roa

Full Stack Developer and Tech Lead

Co-Founder and VP of Engineering @ Trotter

What makes a web page slow?

Rendering Path

Rendering Path

<html>
  <head>
    <!-- loads external css file -->
    <link rel="stylesheet" href="small.css">
    <!-- loads external javascript file -->
    <script src="small.js"></script>
  </head>
  <body>
    <div class="blue">
      This page sucks
    </div>
        <!-- loads external image -->
    <img src="grumpy.jpg" alt="Grumpy Cat" height="80%"> 
    <div class="blue">
      it's not optimized
    </div>

  </body>
</html>

index.html

Rendering Path

.yellow {background-color: yellow;}
.blue {color: blue;}
.big { font-size: 8em; }
.bold { font-weight: bold; }

small.js

/* contents of a small JavaScript file */

small.css

Rendering Path

Summary

  1. Browser downloads the html file
  2. Browser reads the html and sees that there are one css file, one javascript file and one image
  3. Browser starts downloading the css file and reads it to make sure nothing else is being called
  4. Browser decides it can not display the webpage without first getting the javascript and the image
  5. Browser downloads the javascript file and reads it to make sure nothing else is being called
  6. Browser decides it still can not display the webpage yet until it has the image
  7. Browser downloads the image
  8. Browser now decides it can display the webpage

Rendering Path

What???

Rendering Path

Step 1

  1. Browser downloads the html file

Rendering Path

Step 2

2. Browser reads the html and sees that there are one css file, one javascript file and one image

Rendering Path

Step 3

3. Browser starts downloading the css file and reads it to make sure nothing else is being called

Rendering Path

Step 4

4. Browser decides it can not display the webpage without first getting the javascript and the image

Rendering Path

Step 5

5. Browser downloads the javascript file and reads it to make sure nothing else is being called

Rendering Path

Step 6

6. Browser decides it still can not display the webpage yet until it has the image

Rendering Path

Step 7

7. Browser downloads the image

Rendering Path

Step 8

8. Browser now decides it can display the webpage

 

:)

Let's start

optimizing !!!

Prioritize Visible Content

Prioritize Visible Content

Prioritize Visible Content

"Why should a user wait to see the page just so you can download the CSS, Javascript, images, etc. for your footer when you are not even sure if a user will ever see it?"

Optimization Check List

  1. Prioritize visible content

Optimize CSS Delivery

<html>
  <head>
    <!-- loads external css file -->
    <link rel="stylesheet" href="small.css">
    <!-- loads external javascript file -->
    <script src="small.js"></script>
  </head>
  <body>
    <div class="blue">
      This page sucks
    </div>
        <!-- loads external image -->
    <img src="grumpy.jpg" alt="Grumpy Cat" height="80%"> 
    <div class="blue">
      it's not optimized
    </div>

  </body>
</html>
.yellow {background-color: yellow;}
.blue {color: blue;}
.big { font-size: 8em; }
.bold { font-weight: bold; }

small.css

index.html

Optimize CSS Delivery

<html>
  <head>
    <!-- inline css code -->
    <style>
      .blue{color:blue;}
    </style>
    <!-- loads external javascript file -->
    <script src="small.js"></script>
    </head>
  <body>
     <div class="blue">
      This page is CSS optimized
    </div>
        <!-- loads external image -->
    <img src="grumpy.jpg" alt="Grumpy Cat" height="80%"> 
    <div class="blue">
      but still sucks
    </div>
    <!-- loads asynchronously the rest of the css code -->
    <script>
      var cb = function() {
        var l = document.createElement('link'); l.rel = 'stylesheet';
        l.href = 'small.css';
        var h = document.getElementsByTagName('head')[0]; h.parentNode.insertBefore(l, h);
      };
      var raf = requestAnimationFrame || mozRequestAnimationFrame ||
          webkitRequestAnimationFrame || msRequestAnimationFrame;
      if (raf) raf(cb);
      else window.addEventListener('load', cb);
    </script>
  </body>
</html>

index.html

Optimization Check List

  1. Prioritize visible content
  2. Optimize css delivery

Remove Render-Blocking JavaScript

<html>
  <head>
    <script type="text/javascript" src="small.js"></script>
  </head>
  <body>
    <div>
      Hello, world!
    </div>
  </body>
</html>

index.html

Remove Render-Blocking JavaScript

<html>
  <head>
    <script type="text/javascript">
      /* contents of a small JavaScript file */
    </script>
  </head>
  <body>
    <div>
      Hello, world!
    </div>
  </body>
</html>

index.html

Inline Javascript

Optimization Check List

  1. Prioritize visible content
  2. Optimize css delivery
  3. Inline javascript

Remove Render-Blocking JavaScript

<html>
  <head>
    <!-- loads external javascript file -->
    <script src="small.js"></script>
    <!-- loads external javascript file -->
    <script src="medium.js"></script>
  </head>
  <body>
    Hello
  </body>
</html>

index.html

Defer loading of Javascript

Remove Render-Blocking JavaScript

<html>
  <head>
    <!-- loads external javascript file -->
    <script src="small.js"></script>
  </head>
  <body>
    Hello
  </body>
  <!-- defered loading of  external javascript file -->
  <script defer src="medium.js"></script>
</html>

index.html

Defer loading of Javascript

Remove Render-Blocking JavaScript

<html>
  <head>
    <script type="text/javascript">
      /* contents of a small JavaScript file */
    </script>
  </head>
  <body>
    Hello
  </body>
  <!-- defered loading of  external javascript file -->
  <script defer src="medium.js"></script>
</html>

index.html

Combined

Optimization Check List

  1. Prioritize visible content
  2. Optimize css delivery
  3. Inline javascript
  4. Defer javascript loading

Combine CSS files

Combine CSS files

visibleContent.css

team.css

testimonials.css

footer.css

social.css

Inline code

notSoPrior.css

(async loading)

Combine CSS files

How

merge-css: css merger toolkit for node js

https://www.npmjs.com/package/merge-css

 

shrinker: online app to merge and compress your CSS- and JavaScript-files.

http://www.shrinker.ch/

Optimization Check List

  1. Prioritize visible content
  2. Optimize css delivery
  3. Inline javascript
  4. Defer javascript loading
  5. Combine css files

Combine JS files

Combine JS files

visibleContent.js

team.js

testimonials.js

footer.js

social.js

Inline code

notSoPrior.js

(defered loading)

Combine JS files

How

Grunt - concat: Javascript task runner

https://github.com/gruntjs/grunt-contrib-concat

 

compressJs.sh: Build several javascript files into the one build file

https://github.com/dfsq/compressJS.sh

 

shrinker: online app to merge and compress your CSS- and JavaScript-files.

http://www.shrinker.ch/

Optimization Check List

  1. Prioritize visible content
  2. Optimize css delivery
  3. Inline javascript
  4. Defer javascript loading
  5. Combine css files
  6. Combine JS files

Minify CSS, JS and HTML files

Minify CSS, JS and HTML files

/* sets to yellow the background color*/
.yellow {background-color: yellow;}

/* sets to blue the color property*/
.blue {color: blue;}

/* sets to font size to 8em*/
.big { font-size: 8em; }

/* sets to font weight to bold */
.bold { font-weight: bold; }
.yellow{background-color:#ff0}.blue{color:#00f}.big{font-size:8em}.bold{font-weight:700}

To

Minify CSS, JS and HTML files

$(document).ready(function(){
    
    // Initiate the router
    var appRouter = new AppRouter;
    
    // load initial views
    appRouter.loadViews();

    // Start Backbone history a necessary step for bookmarkable URL's
    Backbone.history.start();

});
$(document).ready(function(){var e=new AppRouter;e.loadViews(),Backbone.history.start()});

To

Minify CSS, JS and HTML files

<html>
    <head>
    </head>
    <body>
        <!-- form for sending new message to admin -->
        <form action="/my-handling-form-page" method="post">
            <div>
                <!-- name label and input -->
                <label for="name">Name:</label>
                <input type="text" id="name" name="user_name" />
            </div>
            <div>
                <!-- mail label and input -->
                <label for="mail">E-mail:</label>
                <input type="email" id="mail" name="user_email" />
            </div>
            <div>
                <!-- message label and input -->
                <label for="msg">Message:</label>
                <textarea id="msg" name="user_message"></textarea>
            </div>
            
            <div class="button">
                <!-- submit button -->
                <button type="submit">Send your message</button>
            </div>
        </form>
    </body>
</html>

Minify CSS, JS and HTML files

<html> <head> </head> <body> <form action="/my-handling-form-page" method="post"> <div> 
<label for="name">Name:</label> <input type="text" id="name" name="user_name" /> </div> 
<div> <label for="mail">E-mail:</label> <input type="email" id="mail" name="user_email" /> 
</div> <div> <label for="msg">Message:</label> <textarea id="msg" name="user_message">
</textarea> </div> <div class="button"> <button type="submit">Send your message</button>
 </div> </form> </body> </html>

RESULTS OF MINIFICATION:
 

Original size: 988 chars

Minified size: 472 chars

Useless chars: 516 chars

Optimization: 52.23%

Minify CSS, JS and HTML files

How

Grunt: task runner (uglifyjs)

https://github.com/gruntjs/grunt-contrib-uglify

 

 

html-minifier: HTML minifier with lint-like capabilities.

https://www.npmjs.com/package/html-minifier

 

 

HighTools: Online minimizer

http://www.hightools.net/minimizer.php

Optimization Check List

  1. Prioritize visible content
  2. Optimize css delivery
  3. Inline javascript
  4. Defer javascript loading
  5. Combine css files
  6. Combine JS files
  7. Minify CSS, JS and HTML files

This is just the beginning...

This is just the beginning

  • Enable keep alive

This is just the beginning

  • Enable keep alive
  • Browser caching

This is just the beginning

  • Enable keep alive
  • Browser caching
  • Content delivery network

This is just the beginning

  • Enable keep alive
  • Browser caching
  • Content delivery network
  • Enable content compression

This is just the beginning

  • Enable keep alive
  • Browser caching
  • Content delivery network
  • Enable content compression
  • Reduce server response time

This is just the beginning

  • Enable keep alive
  • Browser caching
  • Content delivery network
  • Enable content compression
  • Reduce server response time
  • Image optimization
  • And much more...

References

Jhon Jairo Roa

Social

Thanks!

Improving web performance

By Jhon Jairo Roa

Improving web performance

Quick and straightforward tips to improve the performance of your web site or web application.

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