It's interesting how the problem seems to be isolated to the lem.lemmy front-end UI component, not any of the backend API interfaces. Once you've got a browser tab open with the lem.lemmy UI viably loaded inside it, navigating is a snap (since the web page isn't actually being reloaded as you browse, just a bunch of API calls and javascrpt that change the visual elements and content you're looking at). And that's hunky-dory if your browsing style is to move around within a single browser tab all the time.

But for people who like looking at post lists / communities and then open posts in new tabs (like me), I often end up with a bunch of tabs that haven't loaded properly. The API is happy to serve up the media, but the UI just can't handle the load of all the new tab requests. It's frustrating.

I manage to work around it by sticking to a single Lemmy tab when I notice the problem popping up. It's not ideal, but it keeps the site usable during those rough patches.

It's also partially why I use Voyager whenever I'm on my phone. Phone apps are a security consent nightmare, but the mobile web interface needs a ton of work to be as nice as some of the apps.