It would of been far more useful if they measured the systems in terms of dollars, as each system makes different tradeoffs. Certainly when you enable acking you may become bottlenecked on CPU at that point instead of being bottlenecked on disk/kafka. So one thing you can do is move to hardware with higher class CPUs to solve the bottleneck. The system they built is persisting intermediary queues between components in a topology. So while this will reduce CPU load by not needing an acking system, you will need more disks as potentially any of the intermediately queues can start to fill up now, you need to reserve capacity for worst case scenario. Potentially in terms of dollars the tradeoff to use more disks has marginally better total cost.