Playback event bursts make HDR diagnostics query mpv and the display far more often than intended. Schedule samples and display reads from steady-clock completion deadlines, and read both source metadata streams from one node.
The x64 60 fps smoke reduced property sample runs from 21.7/s to 3.25/s. A generated per-frame HDR metadata stream still produced diagnostic changes; these are sampled changes, not per-frame LUT invalidation counts.
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