Rate 7 6 5
7 34.1/s  95% 100%
6 627/s 1739%  94%
5 9770/s 28548% 1458% 
and for factors_wheel of numbers near 32 bits, using an order 7 wheel:
s/iter 4294967291 4294967293 4294967295
4294967291 4.45  61% 71%
4294967293 1.74 156%  25%
4294967295 1.31 241% 33% 
Note that 4294967291 is prime, 4294967293 has 2 large factors, and 4294967295 has 5 factors, the largest of which is 2**16+1.
For 4294967291, and wheel orders 57:
s/iter 7 5 6
7 4.44  16% 21%
5 3.71 19%  6%
6 3.49 27% 6% 
In all fairness, I should probably mention that I've customized my own version of Math::Big::Factors to Memoize results where possible, and to reduce the calls to Math::BigInt::new() for constants.
Note that factors_wheel creates a new wheel every time (what a shame), instead of requiring a wheel reference be passed in. Caching wheel goes a little way in correcting this, without changing the interface.
You might also consider avoiding the use of Math::BigInt where possible, as you don't need numbers that big.
Now, back to the question at hand. For numbers near 2**32, factoring a prime number seems to take 150 times longer than creating the order 7 wheel. Creating the order 6 wheel is considerably faster, and so is the factoring based on that wheel.
I'm not sure where the breakpoint is for order 7 wheels. A casual search hints that it is very large.
QM

Quantum Mechanics: The dreams stuff is made of
