The detection pool shifted its whole array down one slot per incoming sample
once full. Detection is throttled to 2 s but the pool fills in 400 ms, so for
the remaining 1.6 s of every cycle each chunk arrived at a full buffer: 320
copies of 1280 floats per chunk, measured at 24320 whole-array moves per 10 s
of audio, all on the capture thread.
Writing to a ring index is O(1) per sample. Draining walks the ring from the
oldest slot so the analyser still receives the most recent audio in
chronological order - a test feeds a ramp past capacity and asserts the exact
contents, since getting the wrap wrong would splice the waveform and corrupt
every estimate silently.