ViewBag access performance

Question

In a View that accesses the same value from a ViewBag multiple times, is it better to store this value in a local variable rather than frequently access the ViewBag object?

Answer 1

ViewBag is just a dynamic wrapper around ViewData. So when you write ViewBag.Foo you are basically querying ViewData["Foo"]. But since this is dynamic resolution done at runtime there's obviously a cost to it. This cost is something that you should not be worried about because it is so small that it won't significantly affect the performance of your application and I wouldn't bother caching the result into a local variable.

What I would bother with is the usage of ViewBag that I would most definitely get rid of in favor if view models. So instead of writing @ViewBag.Foo you will have a view model the Foo property and inside your view you will simply be working with it - @Model.Foo. And as you know a calling a property getter will be blazing fast. Not only it will be fast but you will benefit from strong typing and Intellisense in your views.