$ PERL5OPT= perl pm_11113750_orig.pl
Benchmark: timing 5 iterations of uv_fits_double3, uv_fits_double_bitfiddle...
uv_fits_double3:  7 wallclock secs ( 6.70 usr +  0.00 sys =  6.70 CPU) @  0.75/s (n=5)
uv_fits_double_bitfiddle: 17 wallclock secs (17.36 usr +  0.00 sys = 17.36 CPU) @  0.29/s (n=5)
46875 46875

$ PERL5OPT= perl pm_11113750_a.pl
Benchmark: timing 5 iterations of uv_fits_double3, uv_fits_double_bitfiddle...
uv_fits_double3:  7 wallclock secs ( 6.75 usr +  0.00 sys =  6.75 CPU) @  0.74/s (n=5)
uv_fits_double_bitfiddle:  6 wallclock secs ( 6.67 usr +  0.00 sys =  6.67 CPU) @  0.75/s (n=5)
46875 46875