=== pygame-0001: add _spritedict shadow dict for O(1) membership/removal ===
N=100   k=100  : defective=0.177ms  fixed=0.007ms  speedup=25.0x
N=500   k=500  : defective=4.625ms  fixed=0.044ms  speedup=104.5x
N=1000  k=1000 : defective=25.347ms  fixed=0.097ms  speedup=260.2x
N=2000  k=2000 : defective=36.851ms  fixed=0.097ms  speedup=379.1x

