Ah ha! So the issue was always going through the error type reflection even for the success path. https://github.com/golang/go/commit/af43932c20d5b59cdffca4540

Ah ha! So the issue was always going through the error type reflection even for the success path. https://github.com/golang/go/commit/af43932c20d5b59cdffca45406754dbccbb46dfa https://github.com/golang/go/commit/af43932c20d5b59cdffca454... I'd be interesting to see the benchmark after that.