After removing all JavaScript, jQuery, add-ons etc. the problem did not disappear. The reason for performance issue is the AJAX update panel used. Are you aware of a work around for this bug in IE11/10?
I have found this one but does not fix the issue in IE?
http://support.microsoft.com/kb/2000262/en-nz
I have completed all AJAX performance optimisation in this article also.
http://lancezhang.wordpress.com/2008/11/15/aspnet-ajax-performance/
<add name="X-UA-Compatible" value="IE=edge" /> (IE=EmulateIE9) does not work.
<!DOCTYPE html>
We have 150 users which will be forced to go to Chrome due to this issue.
Many thanks.