Firstly - my first HN front-page, yay!
So, this was a little unexpected to say the least. As has already been pointed out, this post was written about 14 months ago now, and yes details are a little light. I'll ignore the usual HN hospitality and answer a couple of the more pressing questions:
1. this was a very early MVP at the time, it was not a production-ready piece of enterprise software, so no it was not built for out and out speed in the first instance.
2. yes there were probably much better options than c1.medium on AWS, but see (1).
3. yes it uses off-the-shelf libs, see (1).
4. no the website is not meant to work, I never got round to finishing it up, see (1).
5. sadly, I don't have the original git commit to reference (I was at my private repo limit and removed it) but yes, it was essentially a simple 1-line optimisation. IIRC it was something being evaluated in a loop that didn't need to be. Very mundane indeed. No tools used to identify it, I just knew it was being called a lot.
Ironically, the post was meant as a linkbait to drum up a bit of interest in the tool and see if it was worth developing (hence the tabloid title). It didn't get any traction and so the project kinda halted.
That seems sad if true.