It would be great to get input from @timmse, @itchycode, or @thomas on the performance implications of using PHP code, Shortcodes, or Dynamic Tags (either built-in tags or using them with custom functions).
What are the performance implications of executing PHP code within a code element vs. running it from functions.php?
What are the performance implications of running a custom PHP function through a Dynamic Tag vs. Creating a shortcode and outputting them to a template?