functions versus includes

I just started using PHP and got to think... Without getting into the discussion of "best practices", strictly from a performance perspective, what is faster: a function or an include? For example I have a block of text that needs to appear mutliple times throughout the site. Will I be better off creating a function with its contents and then later just calling the function or, will it be faster (from an execution perspective) for me to create an .inc file that gets included later on? Thanks for the your thoughts.