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View State can really mess you up if you're not careful

When developing complex application in ASP.NET you may end up placing hundreds of components on a single page. You may think hundreds is an exaggeration, however, when placing just couple of components on each field of a grid, the numbers will skyrocket rather quickly. With ASP.NET, any modified state of a component will be automatically persisted to a view state by default. After a few iterations of changes you may end up with very long view state that will take time both to download, and on any postback, it will also take time to upload.

How does the view state work? To put it simply by example - suppose we have a label showing number of search hits in the database. We will initialize label text to display zero. The state is not persisted. When visitor hits search button, text of label will be set to reflect three hits. This is a change to state of label and this value is now persisted in view state. When person searches for nonexistent term, they will submit the view state with the additional label overhead. If in our example number of matches is zero, the label is reset back to its original value, however, since viewstate is in effect, the value is persisted to viewstate.

In previous example, it is easy to understand why would web application seemingly slow down when in use. The view state grows and large amount of data is sent back and forth notwithstanding the fact that it is probably useless to do so. When user searches for new item, it does not really matter that label displayed "37 matches", because this state is not useful in performing new search action.

Scroll down for additional info labeled What can you do about viewstate?

More info: What can you do about viewstate?

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Viewstate is your friend in some cases while in others it becomes your enemy. In both cases you can probably do without viewstate. It is up to you if you decide to almost completely abandon viewstate management and use session management instead, or if you find middle ground with limited view state. I have some suggestions and easy pointers:

You can disable view state in many ways:

When deploying multiple servers, best practices call for quorum resource, such as database, to persist session states. This way, when client fails over to another server, your application can retrieve data from persistent store. In this case you do not want to burden your storage so keep what you need in view state when applicable.

On single server system, you will generally persist session state to memory. Memory is very fast and cheap resource and if your application requires stateful information, consider storing it in session state rather than traveling it back and forth between server and client on every click

If your component setting is determined during page generation and if you do not need previous state of component to determine the outcome, you really do not need any state for the component whether stored in session state, cookie or view state. In these cases consider setting EnableViewState property to false.

Imagine following scenario - you have local application wich requires rather complex amount of data stored in session state. The CPU load on servers is so severe that company expanded to multi server setup. Now you are really hammering at your persistent storage. You could in this case easily move large chunk of session state into view state of Page by deploying constructs such as: