We created a website that relies heavily on Javascript and has quite a lot of DOM-elements.
In all browsers, even IE7 and IE8, this works fine. The user experience is a bit faster and more responsive in IE9, Chrome and Firefox, but even our clients that use IE7 don't complain.
BUT... clients that use a remote desktop complain that our website is much too slow, even when using IE9 on Windows 2008 Server (64-bit). Some pages that normally take only 1 second to load, now take up to 30 seconds! The reason is not a slow internet connection, other websites load quickly, only our website doesn't. And when these clients use Chrome it's very fast, so the problem is somehow in the combination of remote desktop and IE.
Now here comes the strange part : when the button "compatibility mode" is clicked in IE9, our website is fast again!
What could cause these extreme differences in speed?
We thought using <!DOCTYPE html> in IE9 was the best practice, but it seems that in a remote desktop session somehow we should use quirks-mode or force compatibility mode??
Any thoughts on this subject?
UPDATE
We found a solution : disabling CSS rounded corners for IE9 !
(see the accepted answer)