Website having trouble to load content

So I've had this problem for a few days now.. It was only rarely happening at first, but now it's happening more and more and it's making me question what's the cause behind it.

First, i'll like to note that all caching is disabled whatsoever (Varnish Cache on server, Cloudflare caching and caching plugin are all disabled).

Basically, when I try loading my website uncached, sometimes the page will load, but shortcode or image elements will not show up, or will show up with a big delay. And when I say "show up" i mean it litterally, they aren't showing up, but they are rendering (Because I see all the links and the elements as I move my mouse around on the website). This is probably hard to imagine, so I got a screenshot up.

On the screenshot, what you should normally see is the user page :
( ). It would contain an HREF picture (which would show "Charles Eric Vincent" as a tooltip when mouse hovers it) and then the rest of the tabs and info.

But on screenshot, what I'm seeing is just an empty shortcode (All text and menus load up fine) but the tooltips are still showing up with the links. So the elements ARE rendering, but they aren't showing up on my screen for some reasons.

This basically happens with multiple shortcodes throughout my website, but also with basic pictures. For example, the 6 pictures you can see when you scroll down the main page
( ) sometimes don't load up at all (On the blue background). There's no href in them so I can't confirm if they are rendering or not, but they arent showing up for sure.

Have you guys ever seen something like this before ? Do you guys have any solution for this ?

Thanks !