These two things are not mutually exclusive.
The important things to do in this case are figuring out which part of the website is header, nav etc and not refreshing them while navigating.
It is not about performance savings, it's about the user experience. Functionality like this can be baked into websites today (basecamp-next et al), but surely it will get easier (I am thinking semantic element which already tell the browser what is a <nav>).
It is not about performance savings, it's about the user experience. Functionality like this can be baked into websites today (basecamp-next et al), but surely it will get easier (I am thinking semantic element which already tell the browser what is a <nav>).