I've found that the latest version of BBEdit feels quite slow on older machines. That surprised me, as older versions were quite snappy. Unchecking "Check spelling as you type" in the Editor Defaults group of the BBEdit Preferences, though, removed the spinning beachball from my workspace, and BBEdit is now its snappy old self again.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2007051507593070