Here are some interesting crypto performance factoids. We ran some tests to see how many RSA signing operations NSS could do on my work desktop machine. The results were better than I expected:

Using a 1024-bit RSA key: ~ 5,100 ops/sec
Using a 2048-bit RSA key: ~970 ops/sec.
Using a 4096-bit RSA key: ~172 ops/sec

So a good desktop machine can do almost 1,000 2048-bit private key operations. In software!   Note that we were not using a hardware accelerator. Just a good Intel-based CPU, running Fedora 8. Today most SSL web servers use the weaker 1,024-bit keys, though the 2048-bit keys will become more common in the next few years.

Your mileage will vary with the computer, the number and type of CPUs, and other factors that make meaningful performance measuring difficult. I was already convinced that SSL/TLS were fast enough to deploy extensively on a web site and even on entire web sites, but these numbers are icing on the cake.