These days I am working on a very big web application...

In one of my aspx pages I had needed to save lots of data in the ViewState object in order to persist data between postbacks, but when I looked at the rendered HTML, I saw a large hidden field for carring the ViewState.

ASP.NET 2.0 came up with a new feature that helps to reduce the amount of the hidden filed's ViewState data that called: PageStatePersister.

When we add an override the PageStatePersister property and use the built-in SessionPageStatePersister, the behavior of the page remains the same, but the storage used for the bulk of the state data is shifted from the hidden field to session state.

Implamantation instance:

protected override PageStatePersister PageStatePersister
{
   get { return new SessionPageStatePersister(this); }
}

In several cases you'll only want to override this property in your page and to shift the ViewState data into the Sesson object, but if you'll want to use it (wisely of course) on your entire web application? You should implement this property in a particular custom base page and to inherit it to all of your application pages.

The only disadventage that I could think about here is the data existent, session can lose its data and information if its timeout has ended, but ViewState can hold the data forever on the page, because it's hard coded.