This document discusses WordPress theme performance. It provides data from testing over 3,800 themes on metrics like speed score, number of resources, file sizes, and response bytes. The median theme in 2016 had a mobile speed score of 53, 432KB in total assets, and response bytes of 125KB for HTML, 101KB for CSS, and 155KB for JavaScript. Recommendations include optimizing assets by consolidating and minifying files, deferring non-essential scripts, and conditionally loading resources. The document emphasizes including performance in designs from the start and selecting themes that meet defined performance budgets.
7. “These days, even 400 milliseconds — literally the blink of an eye — is too
long, as Google engineers have discovered. That barely perceptible delay
causes people to search less.”
“People will visit a Web site less often if it is slower than a close competitor by
more than 250 milliseconds.”
“Four out of five online users will click away if a video stalls while loading.”
“The two-second rule is still often cited as a standard for Web commerce sites.
Yet experts in human-computer interaction say that rule is outdated. “The old
two-second guideline has long been surpassed on the racetrack of Web
expectations,” said Eric Horvitz, a scientist at Microsoft’s research labs.”
Source: http://www.webperformancetoday.com/2012/03/01/nyt-redux-for-impatient-web-users-an-eye-
blink-is-just-too-long-to-wait
14. Why should you care about
web performance?
• Users are impatient and will leave a site
• It will hurt your brand
• Slow sites cost you money
• Slow sites cost your users money
• Google favours fast sites / punishes slow ones
17. What makes a site feel fast/slow?
• Time to First Byte
• Start Render
• Requests
• Bytes In/Total Size in KB
• Time to first byte (TTFB)
• Start Render Time
• DOMInteractive
• Frames per Second (FPS)
• Load Time (Fully Loaded)
24. Disclaimers
• I’m not a data or computer scientist
• I did not test on actual devices
• Not all themes were tested
• The theme previews are not representative
25.
26.
27. Test setup
• Get a list of all WP themes from wordpress.org
• Load them into a spreadsheet
• Feed preview URLs into PageSpeed Insights
• Add results to spreadsheet
• Draw conclusions
31. Data gathered
• 3875 tested themes (rating, number of ratings,
active installs, last updated)
• mobile/desktop speed score
• number of resources (total, static, images, JS,
CSS, other)
• response bytes (total, HTML, CSS, JS)
• number of hosts
35. Development of Speed Score over time
SpeedScore
0
25
50
75
100
Year
2008 2009 2010 2011 2012 2013 2014 2015 2016
MEDIAN of mobile SPEED SCORE
MEDIAN of desktop SPEED SCORE
36. The median average WP theme assets
in 2016
Other
95,738 Bytes
JS
154,576 Bytes
CSS
101,765 Bytes
Images
57,165 Bytes
HTML
23,483 Bytes
Total: 432,727 Bytes
37. Median Number of Resources over time
Resourcefiles
0
8
15
23
30
Year of last update
2008 2009 2010 2011 2012 2013 2014 2015 2016
MEDIAN of Number Static Resources
MEDIAN of Number JS Resources
MEDIAN of Number CSS Resources
38. Median Response Bytes over time
ResponseBytes
0
125.000
250.000
375.000
500.000
Year of last update
2008 2009 2010 2011 2012 2013 2014 2015 2016
MEDIAN of HTML Response Bytes MEDIAN of Image Response Bytes
MEDIAN of CSS Response Bytes MEDIAN of JS Response Bytes
MEDIAN of Other ResponseBytes
46. Good performance is good design
• Include performance in project documents
• Get designs into the browser as soon as
possible
• Test on real devices
• Collaborate
• Educate
• Advertise
Source: http://bradfrost.com/blog/post/performance-as-design/
47. Select fast themes
• Test themes before you buy them
• Tell developers your performance
budget
• Create a demand for better performing
themes
48. Questions to ask yourself
• Do I prioritise performance?
• Am I willing to pay/work more for
performance?
