It should be avoided by using fasttrack, but you seem like having it enabled alright.
Maybe it is an artifact of the test, or of the device used for it, see this thread (where another possible cure, queues, seems to come out like being often worse than the illness):
http://forum.mikrotik.com/t/i-cant-solve-bufferbloat-issue-with-my-hap-ac2-router/175583/1
and particularly this post by mkx:
http://forum.mikrotik.com/t/i-cant-solve-bufferbloat-issue-with-my-hap-ac2-router/175583/1