There is an Option in the preferences, called „background Audio“. If it is turned on, Audio will be Computed even if miRack is running in the background. Makes total sense for a lot of use cases, live performances ie.
Is ist turned on in your case? If so you can just turn it of, and miRack should be very battery friendly running in the background - without audio of course.
I can confirm this is an issue, even with background processing turned off, and with the sim paused. Battery usage is so high that my iPad charger can’t quite keep up sometimes. I should note that the cpu usage shows something like 0-3% almost all the time, regardless of how many modules are on the rack. It seems that there may be a couple different layers of computation going on, and they aren’t all captured or controlled by the app. iPad Pro 12.9”, 5th gen, iPadOS 26.2.1.