Internet Explorer is trying to help you speed its performance by suggesting that you disable add-ons that take longer than 0.20 seconds to load. But, if you are happy with the performance of how long it takes for add-ons to load, then this peristant notification gets annoying very quickly.
While there is no way to turn off this notification, you can effectivley disable it, by changing the setting for notification to be a higher time value that is acceptable for add-ons to take to load.
This is accessed from the Command bar, not the Menu bar (File, Edit, View, Favorites, Tools, Help). If the Command bar is not enabled, you can add it by right-clicking on an empty space on the Menu Bar, and select Command Bar.
Then, from the Command Bar, select: Tools>Toolbars>Diable add-ons. Change the value of “Tell me when the dealy caused by add-ons exceeds”. Set this to a value that is greater than than the longest time of any of your add-ons.