My notes on an article by Etsy’s Lara Swanson posted to A List Apart, Improving UX Through Front-End Performance
Adding a half-second to a search results page can decrease traffic and ad revenue by 20%, according to Google research
Amazon’s research indicates that an additional 100 milliseconds of load time decreases sales by 1%
Users expect pages to load in 2 seconds; after 3 seconds, 40% of users leave
Lara ran a test on Etsy with a new design that took twice as long to load–and she immediately saw a much higher exit rate and lower conversion rate. But it was good to be proven wrong–it provided a benchmark for the future
Creating 1 sprite for several icons saved Lara 16.6% load time.
Keep CSS clean, using non-semantic names in HTML–this can reduce page load by about 6%. Cleaning up existing CSS can reduce its size by a significant percentage.
WebPageTest.org is a great benchmarking tool.