Another course on another platform that overpromises and underdelivers - it is just noise. I did not want to discuss this subject beyond expressing some surprise. Fraud is a too loaded word, but this fits perfectly here: https://en.wikipedia.org/wiki/Hanlon%27s_razor

Benchmarking is hard. If not an art then at least a distinct skill. It goes beyond just using Bnechmark.Net. It's a good first step but far from enough. Oftentimes one need to make sure a compiler does not optimize away some benchmark paths, e.g. by using volatile field accesses. Especially if you want to avoid overheads and measure only certain things. But here it was so obvious it could be meme-tagged #YouHadOneJob.