MPG has a 1TB Apple SSD in the Mac Pro, and a 1TB SSD in the iMac 5K.
MPG was puzzled why IntegrityChecker 'verify' was running significantly slower on the iMac, which ought to run significantly faster (faster CPU clock with ~1.4 CPUs used). Disk I/O speed is the culprit.
Not that the iMac SSD is slow, but there is a world of difference:
Mac Pro: writes at ~930 MB/sec and reads at ~1180 MB/sec.
iMac 5K: writes at ~693 MB/sec and reads at ~744 MB/sec.
PCIe lanes are 500MB/sec and apparently the iMac 5K dedicates only 2 lanes (1GB/sec) to the flash drive (Mac Pro uses 4 lanes).