IE9 and Symantec Intrusion Prevention / Vulnerability Protection

3 posts, 1 answers
  1. Christopher St. Clair
    Christopher St. Clair avatar
    2 posts
    Member since:
    Oct 2009

    Posted 05 Dec 2012 Link to this post

    Background:  We've recently started receiving complaints from our users about very slow page load times on our web applications using Telerik controls in IE9.  After extensive troubleshooting,  we determined that the cause of the slow down was Symantec's IE add-on, Intrusion Prevention or Vulnerability Protection (depending on which version of the SEP client you're running).  When we disabled the add-on, page load times were instantaneous and when we re-enabled the add-on, page load times shot up to a very unacceptable 12-14 seconds.

    I decided to run IE's profiler to determine what exactly was causing this slow down.  The load times for every Telerik script was about 10 times slower when the add-on was enabled than when it was disabled. 

    Workaround Identified:  Since this slow down appeared to be directly related to the Telerik scripts, I decided to start toying around with the RadScriptManager's attributes.  As it turns out, setting EnableScriptCombine to false has resolved the issue and page load times are now back to instantaneous.

    The idea of combining scripts into one to cut down on network traffic is great and I would like to be able to use that feature again someday which is why I am reporting this problem to you.  Hopefully, you can identify why the combined scripts aren't playing nice with the Symantec Intrusion Prevention add-on in IE9, but at least there is a workaround for now.
  2. Answer
    Dimitar Terziev
    Admin
    Dimitar Terziev avatar
    1266 posts

    Posted 10 Dec 2012 Link to this post

    Hello,

    The reason why script combining is causing such delay should be related to the size of combined request. Probably the Symantec's IE add-on is checking the individual requests, and when the size of the request is relatively big and compressed, it is causing such delay. What might be used as a solution is to enable the CDN support so you could benefit from the caching functionality.

    Greetings,
    Dimitar Terziev
    the Telerik team
    If you want to get updates on new releases, tips and tricks and sneak peeks at our product labs directly from the developers working on the RadControls for ASP.NET AJAX, subscribe to their blog feed now.
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  4. Christopher St. Clair
    Christopher St. Clair avatar
    2 posts
    Member since:
    Oct 2009

    Posted 10 Dec 2012 Link to this post

    Thanks for the follow up Dimitar, that makes sense to me now. 

    All of our applications are on our Intranet, so CDN is out of the question.  However, disabling the combined scripts has the page load times back to instantaneous again, so there is no further action needed.   Hopefully, if anyone else encounters this issue in the future, they will be able to reference this post and save them the hours of troubleshooting we went through to identify and fix this issue.
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