You don't need to restart the rails app when running specs if you use spork. Also ruby 1.9.3 vastly improved rails application boot times over 1.9.2, just in case your slow experience was with 1.9.1.x - 1.9.2.x.
Spork's a fine notion, but it's no panacea. Pretty regularly we would be running down some weird bug only to discover that we had to restart. It doesn't take a lot of 10-minute debugging excursions to eat up all the time that Spork saves on starting tests.
