I have made a fully AJAX-based website that gets a snapshot when you visit the url, but loads the future contents with AJAX. Some pages, however, needs additional JS-files. Therefore I'm thinking about making a dynamic loader. (The main reason why I use AJAX is speed...)

Do I need to unload unneeded JS-files? Will the dynamic loading slow down the website if I just keep adding JS-files without unloading unneeded ones?