<1. let you see all the "New" messages at once before the "New" disappears when you click the '>' link
2. let you read the whole board and let your mouse rest at the same time
3. test the browser's hability to handle such a big page
4. test how fast the server can serve pages and how fast you can receive them
5. being online, while seeming offline to everyone else if you plan on reading the whole 12000 lines