Eight seconds. That’s the average length of time a first-time visitor to a website spends on the site before deciding whether to stay or go, according to Shane Cassells, online conversion expert for Google.

“Eight seconds is not enough time to watch your 45-second corporate video,” he told marketers at the IAB Connect conference in Dublin.

Speed is of the essence. The average amount of time users wait for a page to load before they start “getting angsty”, Cassells noted, is two to three seconds.

“Milliseconds really matter,” he stressed. “If one site opens 250 milliseconds faster than the other, there’s a subconscious belief on the part of the user that the site that goes faster is better.”

Fancy content

Many companies make the mistake of trying to push too much onto their websites just because they can. This often involves sticking up fancy content that distracts consumers from making a purchase, or do what they came to the site to do, or slows down the process so much that they click on another tab instead.

Taking Moore’s Law on the rate at which computer processing speed increases as his model, Cassells proposed “Cassells’ Law”, in which “every two years the amount of content we add to our website doubles, but our users’ patience with our website halves”.