It existed to capture the before/after baseline for the 128->100 thumbnail
change, which it has served. As an ongoing guard it is misleading: a 1000x1000
JPEG decode is ~97% of the 15ms it measures, so the two encoders it would be
reached for are ~2.6% of the signal. It reported a phantom 2.8% regression for
the NRGBA thumbnail change that isolating the scaler disproved.
The per-encoder benchmarks in blurhash/ and thumbhash/ cover the part that
actually changes.
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