That will cache them locally on the users machine so they do not have to be loaded again.
Note the alternate tag, I read in a accessibility page you should not use text like "hidden image" or "arrow" but instead use a symbol if possible. If for example the image is a arrow use > or -> Not sure what would be appropriate for things you want to hide.
On a side note 5-10k image shouldn't take that long to load even on a 56k modem. Might be the PHP script you are using is taking a long time to execute in which case the example I posted will not help.
Thanks. I'll give that a try. I was looking at it more closely and noticed two things.
1. It does not currently appear to be caching the images. In other words, the load times are the same for the first and subsequent loads of the same image. I'll see if the code you provided changes things.
2. The long load times seem to only apply to images I'm hosting on my site. I use other images that are hosted on affiliate hosts. In other words, a book cover pic might be hosted at amazon. Those seem to load instantly. I can't figure why it would take longer to show a pic from the same site than one hosted on another site.
One last thing. Most of the traffic is search engine traffic where people come into one of the interior pages and not the home. The average number of pages visitied is about 5 or so per visit. I think I might need to try to write code using a cookie to cache the images the first time they visit a page but not on subsequent visits.