Including 'traits' templates (like the one below) into headers causes them to hang for long periods of time, almost any time the header is edited (seemingly due to 'creating template instantiations'). The problem is particularly bad for Visual Studio 2013, but affect 2015 as well.
Sorry -- this is fixed in the next build. The problem is due to the unnamed default template parameter. case=94492 The next build is currently being tested. It is available here if you would like access before testing completes: http://www.wholetomato.com/binaries/VA_X_Setup2088.exe