COOK increased conversion rate by 7% after cutting average page load time by 0.85 seconds. Bounce rate also fell by 7% and pages per session increased by 10%. Permalink Share on Twitter

Rebuilding Pinterest pages for performance resulted in a 40% decrease in wait time, a 15% increase in SEO traffic and a 15% increase in conversion rate to signup. Permalink Share on Twitter

Tests of the new, faster FT.com showed users were up to 30% more engaged—meaning more visits and more content being consumed. Permalink Share on Twitter

BBC has seen that they lose an additional 10% of users for every additional second it takes for their site to load Permalink Share on Twitter

Ancestory.com saw a 7% increase in conversions after improving render time by 68%, page weight by 46% and load time by 64%. Permalink Share on Twitter

AliExpress reduced load time by 36% and saw a 10.5% increase in orders and a 27% increase in conversion for new customers. Permalink Share on Twitter

According to Google's DoubleClick, when comparing sites that load in 5 seconds to sites that load in 19 seconds, the faster sites had 70% longer average session lengths, 35% lower bounce rates and 25% higher ad viewability than their slower counterparts. Permalink Share on Twitter

Google's DoubleClick found that publishers whose mobile sites load in 5 seconds earn up to 2x more mobile ad revenue than sites loading in 19 seconds. Permalink Share on Twitter

For every 100ms decrease in homepage load speed, Mobify's customer base saw a 1.11% lift in session based conversion, amounting to an average annual revenue increase of $376,789. Similarly, for every 100ms decrease in checkout page load speed, Mobify's customers saw a 1.55% life in session based conversion, amounting to an average annual revenue increase of $526,147 Permalink Share on Twitter

Optimizely added artificial latency to the Telegraph and saw page views plummet: by 11% for a 4 second delay and 44% for a 20 second delay. Permalink Share on Twitter