I really enjoyed Jeremy Kemper’s talk on wednesday. The sort of talk that has you itching to run home and try out what you’ve seen. All good stuff. For those of you who weren’t there, Jeremy was talking about performance.
There is of course another advantage: instead of your browser caching a copy of prototype.js from every site that uses it, your users will only be caching it once (per version). Chances are when they come to your site it will already be in the cache.
Jeremy also mentioned the importance of putting yourself in your users shoes and seeing what your webapp is like when viewed through a slow or high(er) latency connection. I described one way of doing this alternative a few months ago and it really can be quite the eye-opener.