If the configuration you posted is what you call simple, I don't want to know what you call complex. 
I believe you will have to adapt it to the various Mikrotik peculiarities, if you want it to work efficiently and flawlessly.
I see at first glance in your configuration (not that I understand all of it) several violations of the Twelve Rules of the Mikrotik Club (and of GP & CSA), just in case:
Most are of course not really relevant/important, but the multiple bridges and the use of the "old" wireless (as opposed to the "new" wifi) drivers may - I believe - actually affect negatively performance. (but the nstreme is not an option with wifi, so if you actually need it, the wireless packet is needed).
BTW which RouterOS version are you running?