Template TAG shortcode?

Hi,

I'm optimizing my website. I've noticed that using: add_shortcode function is not recommanded as best practice as it seems generating more page loading & DOM consumption.

Anyway, I would like to know if Template tags located into the page "Element > Hook ex:{{custom_field._thumbnail_id}} use add_shortcode function ? If so, I will prefer add the hook through function.php in order to do not use add_shortcode anymore.

thanks :)