It's 14 years later, and multi-core processors are no longer rare by any means. I was here looking for an updated version or improved gzip that would use multiple cores for compressing a single file, but will mention for others that zstd -T0 -19 filename will do exactly this, "intelligently" using the maximum cores available to do the task. I realize this is not gzip, but then again neither is pigz, so I feel justified in suggesting a solution that is not gzip.