This document discusses ways to optimize WordPress websites for performance. It notes that average WordPress site page sizes are around 2.5 MB. It provides tips for optimizing images, using responsive images, lazy loading images, minimizing, combining and compressing files. More advanced techniques discussed include moving scripts to the bottom of pages, inlining CSS and JavaScript, using HTTP/2, caching pages and objects, and leveraging PHP7. The document acknowledges several additional performance optimization topics were not covered.

1. Aki Björklund
Making WordPress
websites faster

4. © 1998 PhotoSpin

5. Average page is 2225 kB
in size and growing

6. Source: http://www.soasta.com/blog/page-bloat-average-web-page-2-mb/

7. WordPress sites are worse

8. In Finland: WordPress sites
average 2,5 MB

9. Page size matters

10. Page size
does not matter
(that much)

11. Page size
≠
page performance

12. Page performance
≠
server-side performance

15. PRACTICAL TIPS

17. Optimize images

18. Optimize images for
users automatically

19. Never use the original sizes
of uploaded images

20. Prevent users using
the full size image

21. There is a filter for that
function h1_remove_full_image_size( $sizes ) {
unset( $sizes['full'] );
return $sizes;
}
add_filter( 'image_size_names_choose',
'h1_remove_full_image_size' );

22. Built-in responsive
images in WordPress

23. Don’t load images
a.k.a. lazy loading

24. Make browsers
cache resources

25. Minimize,
combine,
compress

28. Minimize,
combine,
compress

29. Minimize,
combine,
compress

30. Minimize,
combine,
compress

31. Advanced stuff

32. Move scripts
to bottom

33. …with WP Simple
Asset Optimizer

34. Moving scripts
add_filter( 'wpsao_move', function () {
return array(
'jquery_json',
'gform_placeholder',
'gform_gravityforms',
'optin-monster-api-script',
'wp-mediaelement',
'visualizer-google-jsapi',
'visualizer-render'
);
} );

35. Inline CSS and
JavaScript

36. Inlining
add_filter( 'wpsao_inline', function () {
return array(
'modernizr',
'h1-stylesheet' => array(
'replace' => '../../',
'with' => get_template_directory_uri() .
'/assets/'
)
);
} );

37. HTTP/2

38. SERVER SIDE
OPTIMIZATION

39. Caching

40. Page caching

41. Full page caching does
not work if users are
logged in

42. Object caching

51. PHP7

52. Topics skipped: CDNs, responsive and
retina images, continuous performance
measurement, inlining images, CSS sprites,
prioritizing visible content, avoiding
redirects, DNS, asynchronous JavaScript…

53. Thanks!
@akibjorklund