There’s a running debate over in the creative office here today. The Research and Development team are questioning the Design team on the configuration of images for websites.
The question is: Should a designer spend time dividing the image into sections so that the webpage is loading up a number of separate files, giving the appearance of a faster page, or should the image remain one file?
The argument against division is that it is not actually faster, it just appears to be and on top of this, you have to write more code for each complete image, which may affect the speed.
I got out of the argument when it got down to “it depends how clean the code you are writing is.”
I know plenty of businesses that do it one way and plenty that do it the other. So does it come down to personal preference, or is one way really better than the other?
A third way would be to use a progressive format, which will show a blurred version of the image, which will sharpen as the image downloads.
If you have graphics large enough to start worrying about download speeds then maybe you should consider different ways of portraying the information. An image shouldn’t really be used if the information can be conveyed to the user just as effectively using plain text (here)
The download time of the entire page will probably be the same if the image is cut up or in one piece, but you mentioned that it appears to be faster, this is simply because you will see several small images all downloading at the same time, but they will be downloading slower. Also cutting up images will lead to accessibility problems, not every web user is an average user and there are other specialist browsers (apart from IE and Firefox; text-readers for blind users, small screen users using smartphones and pda’s will definately be affected, or people who simply prefer to have their images turned off when they browse)