3.06 Speed

Broadband Internet has arrived, does it matter if your web site is slow to load? The answer has to be, most emphatically, yes it does.

No time to waste
How quickly should a web page be displayed? This is highly subjective, different people have widely spread levels of tolerance to delay. Best to satisfy the maximum number so assume that your visitors don't have time to waste.

Caught breath
When someone clicks on a link to your page, there is a degree of anticipation. They are quite likely to hold their breath subconsciously. Try it. How long does it take until you become aware that you are holding your breath and have to make the decision to breath again? Generally five to ten seconds. All very unscientific - but it feels about right empirically.

Connection
Broadband is being promoted heavily but is still not universally available and remains expensive. Assume that your visitors will be using a standard modem. Newer technologies, particularly mobile phones, connect at speeds comparable to a modem

Actual speed
New modems are rated at 56k, 56000 bits per second. The "56K" is a marketing term and represents the theoretical maximum if there was zero length telephone line between the modem and the exchange. Users living close to their exchange and connected by recently installed lines may achieve speeds around 42-46K. If the user is distant from their exchange, if the lines are old or been chewed by the cat, if they have poorly installed extensions, if they are using a long telephone extension lead, if they have other phones connected to the same line. Any or all of these will create interference on the phone line. A realistic estimate of connection speed is half the headline – just 28.8K

In real file sizes
How does 28.8K relate to the time taken for a web page to download?
28800 bits per second is 3600 characters per second - each character takes 8 bits.
3600 or 3.6K is directly related to the size of files on your computer.
A 3.6K file should therefore take 1 second to be transferred with a modem operating at 28.8K.
There are several overheads. Additional data has to be sent and received as the modems talk to each other. Whole blocks of data may be lost as the modems attempt to step up the speed but fail. Probably no more than a 3K file will actually be transferred in a second.

Data moving
So, if your page is going to display in less than ten seconds, how large can it be. At 3K a second it needs to be less than 30K. To display the page completely this has to include all the graphics as well. You can get a lot of text on a 30K page. With careful optimising 30K can represent a reasonable amount of graphic content as well. This limit doesn't mean bare pictureless pages by any means.

Ten second pages
If you start with a text only version of a page you will find that it loads like lightning. Staying under a ten second load tine you will generally have over 20K available for images – that is a generously sized photo at a presentable quality.
On the other hand, If your page has an overhead of java effects, logos, background images and border graphics you will only be able to include a small, low resolution version of the same image.

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