cgo doesn't copy the stack to a "bigger stack" when calling a C function. It just uses another stack, dedicated to cgo, and disallows passing pointers into the

cgo doesn't copy the stack to a "bigger stack" when calling a C function. It just uses another stack, dedicated to cgo, and disallows passing pointers into the stack: https://github.com/golang/go/issues/11089 https://github.com/golang/go/issues/11089 So I think the slowness is caused by something else. Thanks for sharing the benchmark.