Do you think the menu will slow down the system?

Question

PHP

There is a menu with the output of categories and subcategories through php, with a resolution of less than 768px, you need a menu of a different kind to appear, I, with the required permissions, made the menu hidden using display: none;
Such a question, will this menu, although hidden, be executed twice and thereby slow down the system?

Answer 1

Do it through CSS (you can with JS) and everything will be fine!

Answer 2

And what about php? No, it shouldn't! Unless you have tens of hundreds of elements!