I ran into a little problem today, and haven’t figured out a way around it yet.
I had a page that is slow but changes rarely, a textbook case for <cfcache>. So I added the caching statement, and ran it. It looked perfectly fine in Firefox. I went to look at it in IE 7, and the CSS was screwed up (supposed to be a centered aligned design, now all the way to the left).
I couldn’t figure it out. I looked at the source code, no differences. Finally I ran a comparison on the two page sources, and discovered that <cfcache>seems to add a ColdFusion style comment containing the url of the page into source, above the doctype declaration. I couldn’t see how that would cause the problem, so I submitted the source to the W3 Source validation service. It informed me that the comment style invalidates the page, because I was using XHTML 1.0 Strict.
As I see it, my workaround is to set the page to XHTML 1.0 Transitional, or stop using <cfcache> on this page.