OP poses a good question and I don't think it's a simple case of GC vs. no GC. In Nim's case it might have something to do with not using the C int types (PR al

OP poses a good question and I don't think it's a simple case of GC vs. no GC. In Nim's case it might have something to do with not using the C int types (PR already open to fix this: https://github.com/dyu/ffi-overhead/pull/6 https://github.com/dyu/ffi-overhead/pull/6)