On 4 lane SIMD using SSE2 (my core 2 duo laptop)

allOnPct    serial      while           cwhile          improvement
-------------------------------------------------------------------
43.93%      84.1ms      38.6ms(2.18x)   44.6ms(1.88x)   .86
58.24%      78.5ms      31.7ms(2.48x)   36.4ms(2.16x)   .87
69.46%      61.7ms      24.6ms(2.51x)   25.4ms(2.44x)   .97
82.88%      43.1ms      18.3ms(2.35x)   17.7ms(2.43x)   1.03
86.21%      31.7ms      17.0ms(1.87x)   14.2ms(2.23x)   1.19
95.18%      28.2ms      14.2ms(1.98x)   11.2ms(2.51x)   1.27
100.00%     26.7ms      13.1ms(2.04x)    9.6ms(2.78x)   1.36

On a Core-i7 using AVX:

allOnPct    serial      while           cwhile          improvement
-------------------------------------------------------------------
49.25%      206.2ms     33.6ms(6.13x)   34.6ms(5.95x)   .97
61.13%      155.9ms     24.2ms(6.44x)   25.6ms(6.09x)   .95
73.98%       99.1ms     18.0ms(5.51x)   19.4ms(5.10x)   .93
81.24%       71.1ms     16.0ms(4.44x)   15.8ms(4.51x)   1.02
90.91%       61.1ms     13.9ms(4.38x)   13.1ms(4.66x)   1.06
100.0%       57.0ms      9.9ms(5.76x)    9.1ms(6.28x)   1.09