Affect on performance using ViewState

ViewState in ASP.Net definitely affect the performance of the web application. Because it has to load across the postbacks and it will be stored on the client browser.

while there is no published limit to the max size of a hidden field

(implementation of viewstate) and most browsers allow large sizes, some

proxy servers are known to limit them to 4k

It can be compressed. You can see the compression techniques in the below urls:

http://www.dotnetcurry.com/ShowArticle.aspx?ID=67
http://www.hanselman.com/blog/ZippingCompressingViewStateInASPNET.aspx
http://www.codeproject.com/Articles/14733/ViewState-Compression