Sleep-paced threads stall for hundreds of milliseconds when iOS coalesces a backgrounded app's wakeups, and the deadline resets that discarded the deficit left the capture backlog queued until its ring overflowed: regular dropouts that worsen the longer the app stays backgrounded. Pace both 20 ms hands-offs from the AVAudioSourceNode render callback instead (mix via Audio.RunCycle with deviceClockedAudio, capture handoff from the ring), wake the UDP sender on a queue signal instead of a 1 ms poll, and let stalled consumers drop their backlog to the buffer target instead of ratcheting it.