Whilst referencing the excellent HTTP archive recently I came across this rather interesting little stat - http://httparchive.org/interesting.php#max-age.
Over 50% of the assets served by the sites that are crawled by the archive, do NOT set a Cache-Control: max-age value.
When I actually thought about it further however I realised that in all of the Health Checks that we run for customers, this is something that comes up time and time again.
One of the most common recommendations that we make to site owners / developers is to set a ‘far future’ expiration date for static content, or content that is unlikely to change for some time.
The benefits are twofold (and well documented) – repeat visitors get a much faster experience and the sites saves on bandwidth costs because it’s serving less content.
So why is this value so high? Should we be surprised that it IS so high?
It possibly serves to highlight a lack of knowledge or understanding around cache control in general. We often see it (it’s fair to say that over 50% of the health checks that we have completed have made this recommendation in some form or another), so perhaps further education is the solution?
Given all of the ‘noise’ generated by WPO in the recent months I was sure that this number would have considerably reduced since Steve first posted this.
It’s reduced by 1%.