=== sklearn-0001: HistGradientBoosting _check_categories — O(n²) feature_names.index in loop ===
N=100   k=100  : defective=0.097ms  fixed=0.004ms  speedup=24.9x
N=500   k=500  : defective=2.501ms  fixed=0.024ms  speedup=105.8x
N=1000  k=1000 : defective=10.182ms  fixed=0.053ms  speedup=191.8x
N=2000  k=2000 : defective=47.804ms  fixed=0.131ms  speedup=366.1x

