Instances of stuck site loading - only menu and then the page takes 10s - help please

Hello,

So I’ve run into a strange bug of sorts. Sometimes, when I load the page, the header menu loads up immediately but then the rest of the page takes ages to load up (10s). I have no idea why, I’ve done a site speed test audit and it’s pretty good - the only thing I can see is that when I run the test on http version, some bit of JS takes significantly longer than anything else 0.6s but that can’t be the reason, surely?

Does anyone have clue what it may be? I’d most appreciative of the help, I can see that it sometimes is causing bouts of pretty bad bounce rate for the landing page.

https://preview.webflow.com/preview/testing-japcoo-f5ac15fd6623058f269eb8e8?utm_medium=preview_link&utm_source=designer&utm_content=testing-japcoo-f5ac15fd6623058f269eb8e8&preview=09ce0cd544e9ebbc4c1fe643f20f2a50&workflow=preview