Adding views in runtime

Hi there,
I have a simple question

Is there any difference between
-Adding views in runtime
-Or adding them by using layout design editor GUI

Which one of them more preferable for memory & CPU consumption?

And

Is there any solution for adding my views with percentage parameters in the design editor GUI?

Ex :
myView.Top = 20%x

Instead of
myView.Top = 120dip

Thank you