You may have been able to bump the process priority to give that process more scheduler time if it's a critical process in a hot path. Perhaps you tried that though. Definitely have to be careful with it, but always an option to keep in mind!
At least for my operation it looked very much like I would really need to become a BEAM vm expert to make sure things ran smoothly (not just with that but other potential issues I had in the back of my mind as well).
From someone with zero experience in building concurrent systems: isn't this true for every sufficiently complex system? If your system is complex enough, then no general framework will help much, right?