banners load faster without full path URLs, since the full path URL will force a new httpd process on your server and if you are serving a huge amount of traffic this will have an impact on the speed of your server.

speaking of server speed, a good tip to speed things up is to use as much static pages as possible, even if you are running scripts...make sure the script is capable of producing a static page for browsing. This will cut server loads dramatically which will lead to an increase in page loadtimes.