Six hot-path optimizations that reduce per-frame CPU cost:
1. Waterfall color LUT: Pre-compute a 256-entry RGBA lookup table
(bins are i8 = 256 possible values) instead of calling
waterfallColorRgba() per-pixel with HSL→RGB math + Math.pow().
Eliminates ~2000+ HSL conversions per frame across both waterfalls.
2. Noise floor O(N)→O(N log N): Replace .slice().sort() with an
in-place quickselect algorithm for 15th-percentile estimation.
For 1024 bins this is ~10× faster.
3. Reuse spectrum bin buffers: SSE handler and buildSpectrumRenderData
now reuse pre-allocated arrays instead of creating new Array(N)
and .map() allocations every frame. Reduces GC pressure.
4. Cache canvas dimensions: drawSpectrum and drawSpectrumWaterfall
read cached CSS dimensions instead of querying clientWidth/
clientHeight every frame (which forces layout recalculation).
Dimensions refreshed on resize and layout changes.
5. Cache DOM references: getElementById calls for zoom indicator and
minimap elements moved to module-level constants instead of
querying the DOM on every drawSpectrum call.
6. Efficient array trimming: Peak hold pruning uses in-place splice
from front instead of .filter() (which allocates a new array).
Waterfall row trimming uses splice instead of repeated .shift().
https://claude.ai/code/session_01G6wuNCkckbHHsU7w5zCtW2
Signed-off-by: Claude <noreply@anthropic.com>
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