What timing do you have your Ability Action Queue Window? I believe that defaults to 0.5 seconds.
Yes default is 0.5 but it is important to understand that it is not the Queuing of Abilities that is the issue, it is the execution of an ability.
It has nothing to do with this sadly, for example... I cast "Aimed Shot"... about 0.5 seconds after I hit my button it starts to cast (at 40-50 FPS and 20ms Latency). Also, my "next ability" that I am spamming already before the Aimed Shot Cast Time is completed (as to not miss any time between) never goes off and no animation ever happens...
I mean, the whole system is just messed up, not smooth... not responsive.