Fry-time components are a crucial part of flexible presentations. If too much of the presentation is baked into the page and we want to, say in the preceeding example, change the navigational links used in the footer, then you have re-bake all of the pages!The computational overhead incurred by including components pales in comparison to the burden of republishing. Does this conflict with our previous call to pre-calculate that which we can? No, it means we must be judicious of our use of bake-time and fry-time resources!
Defining separate components for as much as possible that presentations share from page to page is a major page architecture problem that must be made by system architects and production management. Too much of the presentation baked into the pages and the presentation is too inflexible. Too much of the presentation calculated at fry time and the per request overhead grows, dragging down performance.