- NoFlush - Usual flow with _Layout.cshtml including <head> and <body>. ViewResult returned at the end of the lifecycle
- SyncFlush - Synchronously flush _Head.cshtml to the client before continues with _Layout.cshtml
- AsyncFlush - Asynchronously flush _Head.cshtml to the client continuing with _Layout.cshtml (supported on ASP.NET 4.5+)
All three approaches wait 1 second before return the final response.