Earlier this year Microsoft released an important hotfix for .NET 4.5:

A .NET Framework 4.5-based application that excessively uses ExecutionContext objects or WCF may result in too many objects being pinned on the Garbage Collector heap. This causes heap fragmentation along with an increase in memory and CPU usage by the Garbage Collector.  ...continue reading ".NET 4.5 hotfix available to reduce memory consumption of Exchange 2013 store worker processes"

Due to a version incompatibility between outlook.exe and mso.dll, a mismatched reference to a data structure causes the “Minimize” button in the navigation pane to render incorrectly, typically extremely large to the point that the navigation pane is "invisible" to the user. The issue only manifests when incompatible versions of outlook.exe and mso.dll exist on the system. ...continue reading "Outlook 2013 Folder Pane Disappears After Installing September 2013 Public Update"