Stored procedures can be a great thing although currently they are not supported in the stable version of MySQL. If your site is slow I would check the file size on images you are using and more importantly how many queries you are using on a page. I noticed your home page is quite long and seems to load a lot of data. If you must use more than 3 or 4 separate sql queries you might want to look into adodb
http://adodb.sourceforge.net for php. You can write cached sql queries for data that might not be updated or refreshed on a regular basis.