From the UI I had no idea.

I think the term bloated is quite misleading. I will only speak for Drupal, but the module system means that code will load only if it has been enabled. It is a large code base, but bloat implies that there is a bunch of code sitting around that detracts from performance. This is not the case.

If you are addressing performance in particular with Drupal vertical scaling like other technology is trivial, throw more resources to it, pay higher cost. Scaling horizontally takes non-trivial sys admin knowledge and Drupal best practices; OpCache, Redis/Memcache, shared file system, Varnish, etc.

I get your dislike of how many here hate PHP, but I think "Hack programming languages" is referring to this:

"Hack is a programming language for HHVM. Hack reconciles the fast development cycle of a dynamically typed language with the discipline provided by static typing, while adding many features commonly found in other modern programming languages."

http://hacklang.org/