VS hung on installing or updating packages may be related to ReSharper8.1 EAP
Recently there have been customer reports of hangs in Visual Studio while installing or updating NuGet packages. It could be related to this issue, if you have ReSharper 8.1 EAP installed.
The solution is to update ReSharper to one of the stable versions such as ReSharper 8.1. If it doesn’t solve the issue for you, please report it to us through http://nuget.codeplex.com.