I'm not sure if this counts as a "static website", since the page is not delivered exactly as stored. It requires JavaScript to actually renders the page, which seems like an overkill.
Kinda, it looks like they add a bit of CSS (basically make everything monospaced & pre) so the Markdown text is visible when JS is disabled (noscript), but in a CSS-less browser (e.g. links) the file is received as HTML, and the Markdown code is directly interpreted as HTML, which makes for an unreadable mess (the whole thing is a single "line" with newlines collapsed to spaces)
You're really better off using a static conversion tool, or using markdeep as a static conversion tool (with ?export)
compared to all the other things your cpu is doing,
and all the time your cpu sits there doing nothing,
the "waste" in this case pales to total unimportance.
you've got a supercomputer; you might as well use it.
An idle core will definitely use less power than one constantly processing. That is what drains the battery in your laptop. I'd rather not spend my battery power if it can be done on the server instead.