I have always used my db connection as a singleton, thinking that it was faster or using less resources.
My ASP.NET MVC projects will have one instance of my EntityFramework Context that is handed to my controllers via Dependency injection or other means.
But is this worth it or even necessary to have my database context singelton, or would it be the same if I as an example have a instance of my context in one or more action filters and then one or more in my controllers?
Edit: When I say singleton, I mean singleton per request.