Is this comparing the same number of cores, or is zlib single-threaded and zstd multi-threaded? For some applications it matters how fast one operation complet

Is this comparing the same number of cores, or is zlib single-threaded and zstd multi-threaded? For some applications it matters how fast one operation completes, but for others, it's much more relevant how much CPU time it consumes, so if zstd needs 1 second on 8 cores for something gzip does in 8 seconds on 1 core, it would be no benefit at all.