The patch fixes the performance regression on Windows. The 1:1 case is better than either 3.2.4 or 3.3.1 downloads from python.org. Other cases are close to 3.2.4, losing at most around 2%. Measurements from 32-bit builds:

## Download 3.2.4
3.2.4 (default, Apr  6 2013, 20:07:44) [MSC v.1500 32 bit (Intel)]
a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/z']148
[0.9251519691803254, 0.9228673224604178, 0.9270485054253375]

a=['C:/Users/Neil/Documents/λ','C:/Users/Neil/Documents/η']148
[0.9088621585998959, 0.916762355170341, 0.9102371386441703]

a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/η']148
[0.9071172334674893, 0.9079409638903551, 0.9188950414432817]

a=['C:/Users/Neil/Documents/𠀀','C:/Users/Neil/Documents/𠀁']152
[0.9154984634528134, 0.9211241439998155, 0.9235272150680487]

## Download 3.3.1
3.3.1 (v3.3.1:d9893d13c628, Apr  6 2013, 20:25:12) [MSC v.1600 32 bit (Intel)]
a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/z']84
[1.107935584141198, 1.080932736716823, 1.079060304542709]

a=['C:/Users/Neil/Documents/λ','C:/Users/Neil/Documents/η']156
[1.2201494661996297, 1.2355558101814896, 1.217881936863404]

a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/η']156
[1.1195841384034795, 1.1172607155695182, 1.1198056163882537]

a=['C:/Users/Neil/Documents/𠀀','C:/Users/Neil/Documents/𠀁']276
[1.2389038306958007, 1.2207520679720822, 1.2370782093260395]

## Local build of 3.3.0 before patch
3.3.0 (default, Apr  8 2013, 14:06:26) [MSC v.1600 32 bit (Intel)]
a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/z']84
[1.0824058797164942, 1.0680695468818941, 1.0685949457606005]

a=['C:/Users/Neil/Documents/λ','C:/Users/Neil/Documents/η']156
[1.2159871472901957, 1.2169558514728118, 1.209515728255596]

a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/η']156
[1.1111012521191492, 1.1091369450081352, 1.1049337539784823]

a=['C:/Users/Neil/Documents/𠀀','C:/Users/Neil/Documents/𠀁']276
[1.2080548119585544, 1.2094420187054578, 1.2138603997013906]

## Local build of 3.3.0 after patch
3.3.0 (default, Apr  8 2013, 14:23:45) [MSC v.1600 32 bit (Intel)]
a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/z']84
[0.8673423724763649, 0.8545937643117921, 0.8289229288053079]

a=['C:/Users/Neil/Documents/λ','C:/Users/Neil/Documents/η']156
[0.9235338524209049, 0.9305998385376584, 0.9229137839304098]

a=['C:/Users/Neil/Documents/b','C:/Users/Neil/Documents/η']156
[0.891971842253179, 0.8971224280694345, 0.9036679059885344]

a=['C:/Users/Neil/Documents/𠀀','C:/Users/Neil/Documents/𠀁']276
[0.9310441918446486, 0.9431070566588904, 0.9355432690779342]