Some interesting bits
http://armor.kiev.ua/fofanov/Tanks/
"What makes T-64-style autoloader notably faster than that of T-72 is the presence of 'sequence' mode. When it is enabled, the loading mechanism continuously loads the rounds of the same type without any gunners intervention. In addition, the rotation of the carousel to get the new round is done immediately after the previous round has been loaded, in parallel with the firing procedure. This allows to perform all the blocking loading operations
in under 5 seconds. T-90 has received similar advancement in autoloader logic.
Advances in the autoloader design along T-64 and T-80 line also include the reverse rotation of the carousel thus allowing much faster cycles when the magazine is partially depleted."
Of course the above does not apply to older T-72s and the accurate representation of barrel fired ATGMs
is a problem in the game, just like ERA.BUT the fact that your T-80UM can pump out rounds as fast as an Abrams is not really a mistake.With an adequate loading plan for the autloader it should be able to do that.