From what I saw, I think for at least a few parsers this might be the case because they are built on generated parser code, and it's just easy to run into unfavorable bits and pieces in the output that way, which can drag down performance completely although 95% of the parser are just fine. Technically there's no reasons why toml parsers shouldn't be just as fast or faster as yaml or even eno. :) In any case I'd be happy if the benchmarks stir up some movement and maybe kick off some high performance toml parser intiative, toml is an awesome format and also 0.5.0 was just officially released so there's a good reason to update the parsers now anyway. :)