Understanding Postbacks in ASP.NET

Question

For example,

If I have a textbox with runat=server on a page, The value will be posted back to the server so I can access the properties in the code-behind.

However, under the following situations, does it still hold true?

• A textbox with runat=server but does not appear in the function that is post back to. For example, a button is also on the page, when clicked a post back occurs and within the method that is raised, this textbox was not used.
• Within a MasterPage, will a textbox residing on the Masterpage itself be posted back?

Because just thinking, isn't this mechanism bloated in nature?

If all input controls and its value are posted back on every single button click (even when the input control is not needed), doesn't this deteriorate performance?

Having just one Form Tag on the page really restricts us to using this mechanism?

Answer 1

Truly Understanding ViewState is a must read article on the subject of ASP.NET ViewState

Answer 2

There are several options to cut down on the bloat (and yes, there's a lot of it when dealing with lots of controls):

1. Use AJAX to post only the items required - although be careful to allow clients that don't have JavaScript enabled to still use the page/ site.
2. The MVC framework allows multiple form tags to be used so you can group sections if needs be.
3. Set the EnableViewState to false on pages/ controls.
4. Break up your pages into smaller ones.

Additionally, check out this brilliant graphical representation of the Page Life Cycle in ASP.NET.