The 1.2.0.27-4vmw.550.0.0.1331820 driver did significantly improve congestion and improve latency in general over the intel-nvme drivers. I'm still seeing an issue where sequential writes and limited to no higher than 250MB/s from VM guests, but only with checksum enabled (disabled i get 800MB+ write speed). Maybe a raid controller or raid driver as I'm using Dell/H730 which isn't on HCLed for 6.2 yet, latest I heard from support is that Dell/VMware may have my raid controller added to 6.2 HCL by end of May.
