No, the speed itself isn't the only issue. It would also increase server load, and that's not a per-user problem.
quote:
Originally posted by Chaotic_Shield
Is that because it's requesting the same image 6 zillion times? Or just because of the image itself?
No... the image would only be downloaded once and then cached. The problem is that the script has to search the database to find a post by you for every thread that it displays.
If you want to view a list of 30 threads, MySQL has to look for 30 possible posts. In a database with 60000 posts, that can take a while.