Hello. I have exactly the same problem. ISP gives 300Mbit, but my maximum with 951G-2HnD is around 150Mbit. Fasttrack rules don’t help, the only difference is CPU load becomes lower: ~30% with fasttrack rules and ~90% without (with queues). Any suggestions what it can be? Generally speaking, can speed be limited somewhere else except queues? Because it doesn’t look like a hardware limitation. But review of exported config showed me nothing suspicious.
This solution http://forum.mikrotik.com/t/strange-limit-to-throughput/87608/1 didn’t help (changed pfifo for ethernet-default, changed only-hardware for lan and wan interfaces with ethernet-default)
This solution http://forum.mikrotik.com/t/rb951g-2hnd-wan-to-lan-performance/96164/1 didn’t help either (used another media converter, both are 1Gbit, used different SFPs)