Depending on the size of the viewstate, transmitting your viewstate across a network can entail a performance hit. You can check the viewstate for any control on the complete page by enabling tracing using the Page directive:
<%@ Page Trace="true" ... %>
To disable viewstate maintenance for a page, use the following Page directive:
<%@ Page EnableViewState="false" ... %>
To disable viewstate maintenance for a single control, use the EnableViewState property:
<ASP:Datagrid EnableViewState="false" ... runat="server"/>
To disable viewstate maintenance for an entire application, change the setting in web.config :
<pages enableViewState="false" ... />