Author here -- I agree that const is better. The perf difference I encountered was due to the static keyword though, which is why the blog post talks about that specific issue.
Advocating 'static' when your actual intent is 'const' does less experienced readers a disservice; they will assume that 'static' is meant to make things faster, and be disappointed when it doesn't work for non-constant values.
If anything, the title is meant to be read as "isn't it amusing that something apparently unrelated such as `static` causes a performance improvement".
That said, I have added a note clarifying this at top of the post now.