From: FAQ server on
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FAQ Topic - Why are my rollovers so slow?
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Images are cached by the browser depending on the headers sent by
the server. If the server does not send sufficient information
for the browser to decide the image is cacheable, the browser
will check if the image has been updated every time you change the
src of an image (in some user settings). To overcome this you
must send suitable headers.

<URL: http://www.mnot.net/cache_docs/>


The complete comp.lang.javascript FAQ is at
http://jibbering.com/faq/

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