Not possible - the back end task (BRU) is managing the communication with a tape drive that can take minutes to weeks. With the capacity points of LTO-7 and LTO-8, users often start a job on Friday, let it run, and then come in Monday for the tape change because the first tape filled. BRU must be patient and wait for the user to respond to the tape change request. If they only delay until the next morning, things are mostly good, but if they wait 2 or 3 days the BRU process zombies and we lose communication with it on the UI. There’s no way to stop or suspend the thread as that then prevents BRU from recognizing the tape change and continuing.
We already kill App-Nap and set the sysctl flag for debug.lowpri_throttle_enabled to 0 (off). These QoS messages were new and there’s nothing that I can locate on developer.apple.com that helps.
Of course, there’s this - Minimize Timer Usage and this Energy Efficiency Guide for Mac Apps, but since we don’t have a way to set the Task info for a shell, I don’t see a way to do what we need to do.