ASP.Net / C#, Loop through certain controls on a page?

I am currently looping through all the controls on my page and setting certain types (TextBox, CheckBox, DropDownList, etc.) to Enabled=False under certain conditions.
However I notice an obvious page load increase looping like this. Is it possible to only get certain types of controls from the Page.Controls object rather than Loop through them all? Possibly with something like LINQ?

Change User Password in ASP.NET Forms Authentication

I code in C# (ASP.NET) and am using Forms authentication.
I would like to know which is the best method to change a user password without using the asp:ChangePassword control.
I dont want to use the reset password method.
I just want to grab the password i have inside my textbox and replace it with my older password.
Please note that the PasswordFormat I use is passwordFormat=”Hashed”
Some code snippets would be helpful