Landmark research from Akamai analyzing 10 billion user visits to top retailers. Key finding: a 100-millisecond delay in page load hurts conversion rates by 7%. A 2-second delay increases bounce rates by 103%. Desktop pages loading in 2.7 seconds achieved peak 12.8% conversion—just 100ms slower dropped conversion 2.4%.

Session length data is equally striking: 1 second slower than optimal = 25% shorter sessions. A 2-second delay meant 51% shorter mobile sessions, 47% shorter desktop sessions. This research (from Akamai/SOASTA) provides the granular millisecond-level data that justifies performance investment.

A 100-millisecond delay in website load time can hurt conversion rates by 7 percent. A two-second delay in web page load time increases bounce rates by 103 percent.