I'm a bit skeptical of the results of that paper without the seeing the source code and in what contexts they are performing the comparison. One can always find situations where one scheme is faster than the other but I'm not totally sure if micro benchmarks are representative of the real world. In long-lived servers, ref-counting can be preferable because it avoids random pauses. Maybe it's a latency vs throughput performance dichotomy. But yeah, thanks for posting that.