I'm guessing you're getting downvotes because it's a trivial reply that doesn't add to the discussion.

One could make the argument that Hexo is fast because it's:

- fast to compile: probably faster or equal to industry standard Ruby/Jekyll

- fast to install: npm

- fast to deploy: single command for Heroku / GitHub Pages

- fast to write: Markdown

You're taking the one word "incredibly" and blowing it out of proportion. We're not talking about super computing here, fast is a relative construct.