Improve performance using masterpages and base classes?

[Guest]

I have 2 questions relating to website design in asp .net:

1. In a website that I am building I have everything as a user control. Even
the header, which contains the navigation tabs is in a user control which is
placed on every page. Originally, the reason why I chose to do it this way
(instead of placing the header in a master page) is because my header tabs
change dynamically based on who the user is. My question is, am I losing
performance by doing it this way? Would putting the header in a master page
improve performance? And if I I do put the header in the master page, how do
I change it dynamically?

2. On each of my controls, in the PageLoad method I check for some query
strings (like who the user is, etc), and store them in variables. And they
are the same in every page. Would the performance be any better if I put all
this logic in a Base Class and inherit each page from the base class, and
have the user controls in the page reference the variables in the contianing
page? Please note that I'm asking this question in light of performance, and
not design principles.

Thanks!