It is worth keeping in mind that perl's test suite is not designed for benchmarking, and probably spends the majority of its time doing things very unrepresentative of any kind of normal workload. So while these timings may give a rough indication which build options are likely to be faster, any specific real workload will have its own unique set of timings which are unlikely to map closely to these figures.

For one $work application a few years ago, we came up with a figure of about 25% speedup for a perl built without threads, for example. (That was probably around perl-5.18.) There's really no substitute for testing things on your own workload (which I think @Tux was saying, but not sure the message got through :).