Real world demos of gzipping, minifying, caching. Combined with a tutorial on CSS spriting (right down to 1 image file like google and others) to reduce HTTP requests, linking to images from multiple sub domains to allow then to be downloaded in parallel (current limit per domain is 2), even PNG optimisation to squeeze out every Kilobyte.
It could be done as a panel with a bunch of speakers. I would be willing to speak or contribute in some way.