http://forum.mikrotik.com/t/ax-hardware-speed-limit/183593/15
cross posting this. on 7.18.2 and 7.19.rc2 this is still in issue. very low (for 'ax) TCP tests. Even UDP tests are less than half modulation and aren’t hitting gigabit interface limits. ie, 850Mbps UDP peak (with 10% packet loss reported by iperf) would be more like 940Mbps if it were a 1G ethernet port in the way.