Caching is also vastly underutilized, most apps are read-heavy and could serve a significant portion of their requests from some form of caching.

> When there are performance issues, 95% of the times they come from the database, not the language.

Eh, statements like these are always too hand wavy. Resource usage has to do with performance, the DB has no fault in it but the runtime does.

Having worked with Rails a ton there’s a very large overhead. Most apps would see a significant speed up if rewritten in a faster language and framework, with no changes to the DB whatsoever. The amount of memory and CPU expended to the app servers is always significant, often outweighing the DB.