It takes a long time to load the webpage and you experience high CPU usage when a webpage uses the following CSS pseudo-selectors in Internet Explorer 11:
:hover, :first-child, :last-child, :nth-child, :nth-last-child, :first-of-type, :last-of-type, :nth-of-type, :nth-last-of-type, :only-child, :only-of-type
To resolve this problem, install the most recent cumulative security update for Internet Explorer. To do this, go to Microsoft Update. Additionally, see the technical information about the most recent cumulative security update for Internet Explorer.
Note This update was first included in the December cumulative security update for Internet Explorer (MS14-080).
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
See the terminology that Microsoft uses to describe software updates.