How does it compare to xxHash? https://github.com/Cyan4973/xxHash

Comparing MetroHash to CityHash is not really fair. Why would anyone use CityHash in 2015?

My smhasher fork has both: https://github.com/rurban/smhasher/

Comparable results for xxHash and the new metrohash will be uploaded soon. These things take time.

But I'm more interested in comparing it to HW CRC32-C, the fastest and best hash so far, 2x faster than metro.