Average speed of optimised_corr2.m for different block sizes
Sample was taken over 25 runs for each value

1,5.3358
2,4.9888
4,4.8514
5,5.0443
8,3.886
10,3.7995
16,3.9583
20,3.8307
25,3.6979
32,3.6006
40,3.5281
50,3.4732
80,3.4583
100,3.4471
125,3.4073
160,3.6386
200,3.6382
250,3.6326
400,3.5475
500,3.5546
625,3.5503
800,3.5585
1000,3.5229
1250,3.5219
2000,3.556
2500,3.5526
3125,3.5672
4000,3.5305
5000,3.5368
6250,3.5457
10000,3.5572
12500,3.6311
20000,3.6677
25000,3.7045
50000,3.9113
1e+005,4.3702