This document provides tips to deliver fast performance on mobile web. It discusses how network, browser, and server-side factors can impact page load times. It also provides recommendations like preloading critical resources, reducing payload sizes through image optimization and code splitting, and implementing a service worker for caching to improve performance for returning users. The goal is to help developers understand how to optimize the user experience on mobile.

1. 3 Tips to Deliver Fast Performance
Across Mobile Web
Stefan Baumgartner @ddprrt
Klaus Enzenhofer @kenzenhofer

2. Who we are

3. 4.5 sec 15 sec
Why?

4. Network
Same Page
4.5 sec 15 secSanity Check
Browser CheckChrome 49 Chrome Mobile 33
Server Side
Local WLANLocal WLAN
Only difference is Browser & Device

5. Why did they look at the performance
on the mobile device?

6. Google - Mobile Friendliness Campaign?!

7. Change in their
compensations plan!

8. Contract SLA:
Average Response Time < 3 sec
User
on Desktop + Mobile

9. Good idea?!

10. Let’s talk about
response time

11. Network
Same Page
4.5 sec 15 secSanity Check
Browser CheckChrome 49 Chrome Mobile 33
Server Side
Local WLANLocal WLAN

12. 4.5 sec 15 sec
UserDeveloper Operator

14. Let‘s take a look at the timings!
Navigation Start: 0 ms
Domain Lookup End: 269 ms
Connect End: 330 ms
Response Start: 517 ms
Response End: 518 ms
Dom Loading: 519 ms
Dom Interactive: 519 ms
DomContentLoaded Event End: 520 ms
Dom Complete: 520 ms

15. 0.5 sec 0.5 sec
Developer

16. User Operator

17. User

19. DNS Lookup
Initial
connection
TTFB
(HTML)
Download
Life of an URL request

20. Starting here, we are able to
control …

21. <script src=“angular.js”> blocking!

22. <script src=“angular.js”> blocking!
<script src=“main.js”> blocking!

23. <script src=“angular.js”> blocking!
<script src=“main.js”> blocking!
start render

24. <script src=“angular.js”> blocking!
<script src=“main.js”> blocking!
start renderresponse time

25. The impact of a
JavaScript error

26. <script src=“angular.js”> blocking!
<script src=“main.js”> blocking!
start render?

27. Important content first
Everthing else is an enhancement

28. Single page application frameworks are aware
of this trend
- As long as you have valid routes (= URLs), you have
the ability to render the state on the server
- The first two requests are the document and the
styles of your application
- Then the JS framework kicks in

29. Server-side
rendering for SPA

30. Browser
App
ServingassetsAPIServer
GET /app
JavaScript payload
GET /api/users
JSON payload
GET /api/posts
GET /api/pages
JSON payload
JSON payload
Send index.html
Request JS application

31. Browser
App
UniversalrenderingAPIServer
GET /app
JavaScript payload
GET /api/users
JSON payload
GET /api/posts
GET /api/pages
JSON payload
JSON payload
Initial render HTML + CSS
Request JS application

35. 4.5 sec 6 sec
UserDeveloper Operator

36. Operator

37. The CDN bill exploded!

38. 285 Resources for an initial Page Load
151 CSS and 121 JavaScript files

39. ~200 Resources had larger Header than Body

40. User

41. Mobile Data is
expensive

42. https://whatdoesmysitecost.com

44. http://cdn.shopify.com/s/files/1/1462/9702/articles/26_cangoroo_1024x1024.jpg?v=1473016235

45. Back Home

46. Back Home

47. HTTP Archive – Transfer Size Trend
http://httparchive.org/trends.php
Average Size ~2 500 KB
By 1.6 € per 100 KB
40 € to get started!!!!

48. 2. Page weight

49. There’s lots of ways to reduce
the payload

50. Responsive images

52. <img src=”screenshot-600.png”
srcset="screenshot-200.png 200w,
screenshot-400.png 400w,
screenshot-600.png 600w,
screenshot-800.png 800w,
screenshot-1000.png 1000w,
screenshot-1200.png 1200w,
screenshot-1400.png 1400w,
screenshot-1600.png 1600w”
sizes="(min-width: 900px) 50vw, 100vw"
alt=”Super screenshot of our product.">

53. <img src=”screenshot-600.png”
srcset="screenshot-200.png 200w,
screenshot-400.png 400w,
screenshot-600.png 600w,
screenshot-800.png 800w,
screenshot-1000.png 1000w,
screenshot-1200.png 1200w,
screenshot-1400.png 1400w,
screenshot-1600.png 1600w”
sizes="(min-width: 900px) 50vw, 100vw"
alt=”Super screenshot of our product.">
These sources are available. For each “width unit”
there’s a reduced version of our original screenshot
The sizes define which source to choose from. Retina screens
are also checked
A low-res fallback image for browsers that don’t know srcset

54. Reduce styles

56. Tree shaking

60. 4.5 sec 6 sec
UserDeveloper Operator

61. 3. Now for the
returning visitor

62. Service worker

66. if ('serviceWorker' in navigator) {
navigator.serviceWorker.register('/sw.js')
.then(function(registration) { // Registration was successful
console.log('ServiceWorker registration successful with scope: ', registration.scope);
}).catch(function(err) { // registration failed :(
console.log('ServiceWorker registration failed: ', err);
});
}

67. self.addEventListener('fetch', function(event) {
event.respondWith(
caches.match(event.request)
.then(function(response) { // Cache hit - return response
if (response) { return response; }
return fetch(event.request);
})
);
});
var CACHE_NAME = 'my-site-cache-v1';
var urlsToCache = [ '/', '/styles/main.css', '/script/main.js' ];
self.addEventListener('install', function(event) { // Perform install steps
event.waitUntil(
caches.open(CACHE_NAME)
.then(function(cache) {
console.log('Opened cache');
return cache.addAll(urlsToCache);
})
);
});

69. 2 sec 2.5 sec
UserDeveloper Operator

70. 4.5 sec 15 sec
UserDeveloper Operator
UserDeveloper Operator
How to?
2.5 sec2 sec

71. 4.5 sec 15 sec
UserDeveloper Operator
UserDeveloper Operator
How to?
2.5 sec2 sec
Happy Developer != Happy User
Your user might travel and mobile data is expensive
The returning user will appriciate your
caching strategy

72. You don‘t know how happy your users are?
https://www.dynatrace.com/trial/

73. Thank you!
Stefan Baumgartner
@ddpprt
Klaus Enzenhofer
@kenzenhofer