The current best practice for solving that is to flatten your WordPress installation in HTML files, or to use a WP cache plugin. Caches like CloudFlare also help a lot.

I don't know the exact details about it, but that solves the bottleneck. Once pages are flattened they do not have to call the database again.

There's also a flat-file CMS called FlatPress, but I was not able to reliably determine if it's a fork or not.