Be patient and wait or get a PC?
I'm guessing that you have just visited the forum/thread for the first time and do not have a cached version to rebuild the page. Also I've seen this before on vBulletin sites, if not others, it's just the way your page loads.
My PCs have 4-8GB of RAM now, regardless of operating system, which you haven't mentioned and it could matter. I use Windows 7, 10 and Linux Mint 19.2 with Firefox 66.0.2 or whatever Mint has at the moment (FF is configured for Linux Mint by the distro). I would expect mobile devices to load differently due to their OS and small screen sizes as well as which display version of the vB format you are using (hint: try changing it and see what happens).
Note that threads that are heavy on images will take longer to load, cached or not.
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I don't know nothing, and I memorized it in school and got this here paper I'm proud of to show it.