1) Set debug=false under compilation as follows:
2) Use Server.Transfer instead of Response.Redirect.
3) Always check Page.IsValid when using Validator Controls
4) Use Foreach loop instead of For loop for String Iteration.
5) Use Client-Side Validation. (but not all the time you have to validate even on the server side)
6) Check “Page.IsPostBack”. To avoid repetition code execution.
7) GIF and PNG are similar, but PNG typically produces a lower file size. (True, but some browsers not supporting PNG format)
8) Use the AppOffline.htm when updating binaries
9) Turn off Tracing unless until required. (by default it's off, use on the pages where it's required)
10) Precompiled pages and disable AutoEventWireup; setting the AutoEventWireup attribute to false in the Machine.config file.
