Some nav items with identical class and no interaction has a delay when clicked on

Could anybody help me out. For a client I manage this website: https://swissborg.com. So the project was already set up by somebody else and I complete redid it. But there is one strange behaviour. When you click on ‘about’ or ‘blog’ there is a delay in loading the new page. When you click on the homepage or products there is no delay.

I’ve changed the destination from /about to an external link and it does the same. When you click it it take 200/300 ms before loading the page.

Anybody has similar issue and know how to fix it?