In Google sheets case, because they are being processed through two separate transformation pipelines, then they compare the result from different runtime environments (i.e. server vs client). The automated translation via J2CL is surely producing very suboptimal code in JS versus Wasm. The end result doesn't matter if it's incomparable.

In Amazon's case, are they using specialized vector instructions (i.e. SIMD) in the Rust version, different graphics apis, specialized algorithms? They just said it's 10 to 25 times faster with no code. Ok...sure.