We have the exactly same issues with 8x Dell R760 Server and Dell PERC12 RAID Controller H965i. Extreme high latencies in local RAID with 6x NVMe SSDs. Tried different VMware Versions with Dell customized Image. From 7 to 8 and so on. It seems that there is Firmware Problem or Driver Problem with esxi. At the moment These systems are useless because Performance is slower than in SATA Drives.