Hello.
Ive upgraded most of my network devices to 6.35.2. I think it was very idea at the end. Part of those devices worked quite well on 5.25 (like RB750UP). Other on 6.27 was working properly too. Anyway I see that current sofftware puts a lot more "stress" on CPU each of the device. I run auto configuration backup script 2-3 times a week, and every time It runs (in the night) i see lots of alarms in nagios logs, like high ping, lost packets and the worst thing is... that devices disconnects, just like that (during export), And dont tell me its because device is overloaded… Yes its overloaded by something during export, that puts a lot o stress on cpu, its not high traffic case, because in those places after midnight only arps “fly” if you use /export command for example on RB750UP its gonna export just half of config and besides it takes eternity (simple config with 4 ports bridged and export “hangs”) Isint something wrong here? Iheven`t seen such behavioer before…
Not only you see this. But mikrotik still believe that it doesn’t matter. You can find this topic already discussed here.
I do notice that /export takes a long time on slow devices like RB750, but the same thing is usually true on other manufacturer’s routers (e.g. Cisco).
What I have not yet noticed is that it causes operational effects like lost or delayed packets, or that the export would fail or be incomplete.
I cant` find anything related export issues 
Could you give me direct link? Anyway, this problems make me so mad Do downgrade will help in this situation?
I do not understand you cannot find relevant threads. The first link I got from google was this:
http://forum.mikrotik.com/t/100-cpu-load-when-do-export/96015/1
How it is possible the people cannot spend 5 seconds on google, but rather spending many minutes writing “new” things again and again?