Yea... libraries are always good (especially for math and analysis), but I find that powerful languages need far fewer libraries to get things done. APL can do something with a few characters that might commonly be implemented as a lengthy function or library in some languages.
Windows Powershell can surprisingly do a lot of what Perl 6 can do and people mostly understand the limitations. You can automate processes, build your own DSL, have full OO support, full .NET interop, concurrency, you can pipe data around kind of like with FP...etc. It doesn't have some of the more perlish features though.
I wonder if the JIT will interfere with scripts where startup time is not acceptable?
But if you actually wanted to get the job done idiomatically, the code is one short, simple line of Perl 6. The performance, while admittedly slower, is within the same order of magnitude as your Perl 5 version.
To me, this is the magic of Perl 6. Sure, if you want to use 16 lines of loopy integer-crunching code to calculate the first N primes and you care about speed, Perl 6 should not be your choice. On the other hand, if you'd prefer to say
(1..$N).grep(*.is-prime)
and get the answer back in reasonable speed, Perl 6 is perfect.