If you transfer the functionality over from your template to a common master page, I would suspect that your performance won't be impacted, good or bad, though it sounds like that you will reduce from two or three user controls to one master page.
On the other hand, the maintenance time may be reduced by using the master page approach. Thus, I would say that transferring to a master page would be a waste of time.
Christopher Reed
"The oxen are slow, but the earth is patient."