I have recently moved my dedicated server to a new provider. I mostly did this for pricing reasons, but there’s also the benefit of network speed, as most of my visitors and now – the server itself – are in Europe. This move, coupled with a few optimizations, has opened my eyes towards some data – the impact of page load time on “pages per visit” metric. While the general theory behind the relationship of the two is clear to everyone, the actual numbers did shock me.

There is a small community that I am hosting – it has roughly 2000 members, who are pretty active. As the community does not accept any new members, the results reflect just the engagement based on page load speed. I did not really take measurements, and Webmaster Central page speed lab tool is unable to provide the numbers due to the closed nature of the community, I estimate that the average full page load time decreased from some 8-12s to 3-5s. The effect on pageviews? PLUS THIRTY FIVE PERCENT. There is no change in the number of visits (sessions), but the number of pageviews is up by a third instantly. Check out the graph:

There is one more statistically significant website that I had a chance to test. This time, the page load time decreased from 5s to 1.5s. Yet again – the pages per visit number is up by 12%. Now, here’s the best part of it all – the two websites are somewhat related (you may call them “affiliates” if you’d like). Since both of them had substantial speed improvements – the referral rate from one to the other has actually increased… threefold.

While I must say, that the actual time on site has not increased as much, the pageview count is what matters a lot if you’re participating in PPC. Funny thing, is that if you are actually participating in Google AdSense – that will be the bottleneck.

At the end of the day – the overall user experience improvement is quite immeasurable and the pleasure of having your visitors tell you “wow this is fast” is indescribable.

Worried about premature optimization? Well, it still holds true that you should only optimize where it hurts.