After running a few quick tests to see how my new site is performing, with only a few minor optimizations (bundled css and js not minified and a few image sprites) load times are around half a second. I also ran the excellent load testing tool Siege. At 500 requests/second load times were still under 2 seconds, all on shared hosting. No chance of getting slashdotted with those numbers.
In the coming weeks and months I'll be turning on CloudFlare for my site, wrestling with Ruby to get css and js minification working and moving over to my VPS running nginx. Load times should be rock solid in the 250ms neighborhood with the ability to serve 1000s of request per second.