Vincent Flanders writes:
"So Why are big images bad? In the September 1997 issue of Windows Source Magazine, Paul Bonner said:
'Pages that take a minute or more to load just don't cut it with the average Web surfer whose attention span for new sites has been measured at only about 8 seconds.'
"UUNET, one of the largest provides of Internet Bandwidth, ran an ad that sums it up: 'Someone just clicked on your Web site. The next fifteen seconds will make or break you.' We should basically split the difference and say the average attention span is 10 seconds— tops <grin>."
The rule of thumb that summarizes the above quote is "8 seconds, plus or minus 2". Where the plus or minus 2 seconds is the usual range of disagreement among the experts.
As the next quote shows, in the years since the above observations were written, user expectations have changed. With those expectations moving away from an Internet that "can be used", towards an Internet that is "really usable".
"There's a de facto rule that page loads should be no slower than six to eight seconds. That rule is too forgiving— sites should deliver pages no slower than 4 seconds.
"In the 1980s, IBM conducted a study that determined successful response rates for what were then terminal-and host-based applications. It concluded that response rates should be no more than 2 seconds. Beyond that, productivity declined significantly.
"I understand the difference between Web-based and host-based systems, but the difference between 2 and 8 seconds is far too much. Our expectations appear to be heading in the wrong direction. I'm also certain we didn't become more patient over the years.
"Can pages load in 4 seconds or less? Is this achievable? You bet. Check out Keynote's Business 40 Internet Performance Index. Sites such as Yahoo, Schwab, and Microsoft average far less than 2 seconds. The Business 40 average is far less than 4 seconds."
For anyone using High-Speed Internet (1 mega-bit/second & up), the goal should be to have each page fully loaded within 4 seconds. Otherwise, the following more general guidelines should describe how each page loads:
All of the above is allowing about 2 seconds of those times just to find then make connections with the Web server— after which the described navigation and content starts to load. For the full context in which I offer the above interpretation, on to "the rest of the story".
Note: I admit to being totally mercenary in my "Quest for Understanding". So when I find something presented "better than I could put it myself", I do sometimes quote extensively from that source— with full credit, and a link back to the original document. (Assuming the original page still exists on the Web to link back to it.)