You have an ASP.Net web-site that has some Crystal Report's files inside of it (and subsequently also probably have some Crystal assemblies in the Bin directory or installed on the server). When I upgraded one of my projects to VS2013 and later VS2015 I noticed that my builds would hang for long periods when it hit the directory where my Crystal Reports were stored. This puzzeled me since the Crystal Reports rpt files aren't actually built into anything, they're content (although I'm using a web-site project and I can't mark them as content like you could in a library project).
It appears that Visual Studio (or Crystal) inserted the following into my web.config (and I'm sure it wasn't me, not directly anyway).
<add type="CrystalDecisions.Web.Compilation.RptBuildProvider, CrystalDecisions.Web, Version=13.0.2000.0, Culture=neutral, PublicKeyToken=692fbea5521e1304" extension=".rpt" />
Find the above section in your web.config file and comment it out or delete it. Sure enough, the next compile will speed along and if you're using the Crystal Reports through the API objects you shouldn't notice any changes in functionality (other than a faster build time while you're developing).