Apparently I'm not alone. In the past four Georgia Tech surveys, web users most frequently cite download speed as the biggest problem with the web. According to May's report, 61% of respondents said web pages take too long to load. And most of these folks have modems newer and faster than mine: only 1.8% now surf at 14.4 kbps or slower (Kehoe et al.).
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Users most frequently cite slow download speed as the biggest problem with the web. |
Jakob Nielsen -- the engineer Web Review calls "master of the usability universe," the web's sixth most influential person by ZDNet's count, a man renowned for his diligence in testing how folks use the web -- Jakob Nielsen has something to say about speed. [1] Studies of hypertexts, he says, show we need response times of under a second to feel we're moving freely through information. That's less than one second between the time we click a link and can begin reading the page. Less than one second! For this response over a modem, a web page would have to be less than 2 kilobytes in size. That's about three hundred words straight text -- forget pictures.
So Nielsen cites a more attainable target: keeping download time under ten seconds. Studies have shown that's how long it takes us to forget what we set out to do. Still, the ten-second target demands a lean 34 K maximum for a web page, HTML and images together. [2] There's just one diet, Nielsen says: designers must limit graphics.
[W]ebpages have to be designed with speed in mind. In fact, speed must be the overriding design criterion. To keep page sizes small, graphics should be kept to a minimum and multimedia effects should only be used when they truly add to the user's understanding of the information (Nielsen).
Just what is a minimal use of graphics? From a speed standpoint alone, perhaps no images might be best. The old saw calls the picture worth a thousand words. Doing the math here, that's three seconds of download time. When have you last come across an image that squeezed itself into 6 K? At modem speeds, words would seem to be the better deal.
Trouble is, images are necessary -- and not just because they improve reading speed. They are necessary as illustration and as spice, even for we techo-grouches who refuse to upgrade our modems. Without images, we lose part of the meaning of the web. We lose much of its joy.
There are indications, too, that images help us remember what we've read.
[1]On the web, Nielsen's columns at http://www.useit.com are a trove of design suggestions and sharp analysis of the webscape (Degenhart), (Berst).
[2]While modem speeds have increased since Nielsen's article, more recent studies concur. Zona Research's June 1999 study recommends a maximum page size of 40 K, based on an average web backbone connect speed of 5 kilobytes per second and a target load time of 8 seconds. Zona estimates that slow-loading pages could cost e-commerce vendors as much as $73 million a month in lost sales to surfers with 14.4 kbps modems (Guglielmo), (Zona Research).