The users have a limit on data transfer for their gadgets

I dont think this is the root cause. Different devices will have different layout for rendering, but usually the same content. Even on a high capacity endpoint with fast internet, it still struggles. My belief is that v14.x contains inherrent architectural flaws.

I've shown for example already the same query being executed multiple times. The proposed solution was to use query cache as a way of mitigating that problem. But as I pointed out, thats contrary to the advice of the MariaDB dev team. There is absolutely no reason to have thousands of database queries to render a single page.

The total database query time is low, but the number of queries is high. Even if the queries are cached, the application layer is still processing thousands of queries. Thats where the inefficiency lives. All of those loops that are doing repetative redundant queries. No amount of tuning will make up for architectural flaws.

Async block handling helps from a pure "visual" perspective, but it still does not reduce page load time. It just helps get the top bit visible sooner. No real solutions without a bigger architectural review.