Passing IEnumerable<Object> to MVC view and casting to strongly typed object

Question

I have a requirement to pass an IEnumerable<Object> to an MVC view and have the view cast this to a strongly typed object and display it accordingly.

This appears to be having a performance impact vs. passing it down as a IEnumerable of MyCustomObject.

foreach (var item in Model.Items)
{
    var current = (MyCustomObject) item;
    <p>@current.Submitted</p>
}

My questions are

1. Should I cast the entire IEnumerable of Objects to IEnumerable of MyCustomObject?
2. How can I improve the performance of this operation?
3. If this is not good practice, what's the best way to pass a "variable" type for my Items collection, which could be a collection of any type of custom object?

Answer 1

Use a List pass this to the model, then it is strongly defined

Controller

public ActionResult Index(){

MyModel model = new MyModel();
model.list = //get list from source

return View(model);

}

Model

public List<MyCustomObject> list {get; set;}

Answer 2

Initially, you could use Cast on the entire collection:

foreach (var item in Model.Items.Cast<MyCustomObject>()){}

If your types will all inherit from a base type, say MyCustomObject, then your model should specify this, eg

public class MyViewModel<T> where T : MyCustomObject, new() 
{
    public IEnumerable<T> Items { get; set; }
}

You would need to ensure that any types you wished to add to your items collection inherited from the base MyCustomObject type