$ perl bench_split.pl
            s/iter       regex       index       split filehandle2  filehandle
regex         3.44          --        -10%        -35%        -45%        -48%
index         3.11         11%          --        -28%        -39%        -42%
split         2.24         53%         39%          --        -16%        -20%
filehandle2   1.89         82%         65%         19%          --         -5%
filehandle    1.80         92%         73%         25%          5%          --