The playing counterpart to the July-18 idle capture: mid-set highlight-stats
shows 580 markers live vs 16 active, accumulating ~40/min (matches July's
34/min idle) — the position-marker pool still never evicts, so the 07-19
"marker leak fixed" is incomplete and the idle 82% renderer burn (the
break-time heat) shares this exact root. UI-smoothness only; audio untouched.