There are four benchmarks in there that compare CRuby and TruffleRuby and two of them are slower. TruffleRuby is 2x faster on bench.b (brainfuck implementation), 3x faster on matmul, 3x slower on base64 and 7x slower on json. All four of these are pretty specific benchmarks. Optcarrot has code that is much more representative of what a Ruby program might look like.