My last post on performance budgets emphasized back-end service latency. Dan Mall’s brief article “How to Make a Performance Budget” does an excellent job giving concrete examples of making a performance budget for asset sizes: HTML, CSS, JS, Web Fonts, images, etc.
(Via. Jakob Anderson)
I’ve had a lot of luck using this article to push performance conversations further. The numbers are dated but the concepts are real.
You have to know how good is good enough. How bad is too bad to tolerate. You have to separate user interactions by value and user expectations. Here I break down user expectations and give some (lenient) standards that ought to be worth discussing (and keep people from setting their hair on fire).
Web Sites Don’t Get Special Dispensation
The guidelines for latency limits are not new. For example, the advice given in Response Times: 3 Important Limits is over 40 years old, but still generally true. In fact, special guidance to web-site operators only tends to emphasize how more and more impatient our users are becoming. Consider these excerpts from a white paper by Gomez entitled Why Web Performance Matters: Is Your Site Driving Customers Away:
The average online shopper expects your pages to load in two seconds or less, down from four seconds in 2006; after three seconds, up to 40% will abandon your site.
Gomez’ own studies reveal [a] lack of visitor loyalty. By analyzing page abandonment data across more than 150 websites and 150 million page views, Gomez found that an increase in page response time from 2 to 10 seconds increased page abandonment rates by 38%.
[The] average impact of a 1-second delay meant a 7% reduction in conversions.
The industry advice continues on and on: incremental decay in performance causes decay in retention and conversion. Slowing down matters. A lot.
Shades of Success and Failure
Continue reading Talkin’ ‘Bout Your Web Perf