Since Rails 7.1 we've had https://www.rubydoc.info/github/rails/rails/ActiveRecord%2FR... which actaully does run queries in parallel.

There's also Rails' russian doll caching, which can actaully results in pages with n+1 queries running quicker than ones with preloaded queries. https://rossta.net/blog/n-1-is-a-rails-feature.html