FWIW, the fastest all-perl prime generator that I've found for small primes (i.e. less than a billion or so) is in merlyn's primes article. If you are serious about performance, I'd recommend reading it carefully.

Update: The link appears to be down at the moment, but I'm pretty sure its correct...
For the impatient, here is a link to the article in google's cache (thanks rob_au)

-Blake