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.
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.