Sometimes when the page loads the header section containing the site logo and nav menu appears at about 3 times it’s normal height. Or the hero slider appears on the page lower than normal so as to give this effect. I’m not sure which of the two it is. Only occurs on the home page. I would attach a screen shot if I could.
Dunno! Still waiting for a response but after closer inspection it does appear that what is happening is the hero slider is appearing lower on the page with a big margin between the top of the slider and the header.