You have a bit of a problem in that last time I looked ActiveState had dropped support for the Crypt:: modules due to legal issues. See here on ASPN which gives you apologies and links to Randy Kobes repository. I don't know if CipherSaber is available as a ppm or not. That repository is down at the moment. I do know it is Pure Perl and as a result it will quite probably be a lot slower than C/XS based modules. Also a ppm is fairly redundant.

In terms of speed why not check yourself? Symetric ciphers are much faster that public/private key algorithms (PKI), in fact things like PGP only use PKI (RSA in that case) to encrypt the key. The rest of the plaintext is encoded with IDEA which is a symetric cipher. With a symetric cipher you have to share the secret key of course. Also you need a key length of about 3N with PKI to get roughly the same security as a symetric cipher key length N. Yes this is a generalisation. No my crypto is not good enough to prove it. I tend to use Blowfish but that is really only because I thought the name was kinda funky ;-) PGP is probably a good option if you want an assymetric PKI. IDEA is probably as good as any in practice for a symmetric.

But what can I say, I get really strange images in my head, and a wierd grin on my face, every time I use Blowfish :=) Twofish is also good, but I like fishing. Twofish2 is less brain dead, or so the author says, and it does have a certain symmetry. Given that 99.99%+ of us have no real idea how secure a cryptosystem is I think choosing a module based on the funkiness of the name is as good an algorithm as most.