Is System.Web.Optimization part of .Net Framework 4.5?
Microsoft is adopting a new strategy with VS2012 in which they are componentizing more of the new features as packages that can be downloaded via nuget. For example, Entity Framework, MVC4, WebApi, Web Optimization, etc.. are all now packages rather than part of the framework.
The reason is that these systems can now be easily upgraded out of cycle with the rest of the framework. Thus, MVC5 can be easily released without waiting for .NET 5, and Web Optimization v2 can be released whenever it might be ready.
Here is a similar question:
Microsoft.Web.Optimization package is now "legacy":
The new package is Microsoft.AspNet.Web.Optimization:
Microsoft.AspNet.Web.Optimization and Microsoft.Web.Optimization are NOT part of .NET Framework 4.5.