I recently found a problem. After pppoe dialing at 10 Gigabit negotiation rate or 2.5g negotiation rate, connecting to the gigabit negotiation rate port, the external network Gigabit speed drops to 700.
Have you encountered the same problem?
My machine is rb5009 and the version number is 7.2 rc4.
Possibly related: http://forum.mikrotik.com/t/rb5009-slow-speed-2-5g-bug-report-as-requested/155362/1
But it could also be something else. Without a full config (/system export hide-sensitive) it’s hard to tell.