The HTTP protocol is stateless; however, server controls provide a rich programming model that manages state between page requests by using view state. Server controls require a fixed amount of processing to establish the control and all of its child controls. This makes server controls relatively expensive compared to HTML controls or possibly static text. Scenarios where server controls are expensive include the following:
- Large payload over low bandwidth. The more controls that you have on a page, the higher the network payload is. Therefore, multiple controls decreases the time to last byte (TTLB) and the time to first byte (TTFB) for the response that is sent to the client. When the bandwidth between client and server is limited, as is the case when a client uses a low-speed dial-up connection, pages that carry a large view state payload can significantly affect performance.
- View state overhead. View state is serialized and deserialized on the server. The CPU effort is proportional to the view state size. In addition to server controls that use view state, it is easy to programmatically add any object that can be serialized to the view state property. However, adding objects to the view state adds to the overhead. Other techniques such as storing, computed data or storing several copies of common data adds unnecessary overhead.
- Composite controls or large number of controls. Pages that have composite controls such as DataGrid may increase the footprint of the view state. Pages that have a large number of server controls also may increase the footprint of the view state. Where possible, consider the alternatives that are presented later in this section.
When you do not need rich interaction, replace server controls with an inline representation of the user interface that you want to present. You might be able to replace a server control under the following conditions:
- You do not need to retain state across postbacks.
- The data that appears in the control is static. For example, a label is static data.
- You do not need programmatic access to the control on the server-side.
- The control is displaying read-only data.
- The control is not needed during postback processing.
Alternatives to server controls include simple rendering, HTML elements, inline Response.Write calls, and raw inline angle brackets (<% %>). It is essential to balance your tradeoffs. Avoid over optimization if the overhead is acceptable and if your application is within the limits of its performance objectives.
