Our forum is set up to automatically resize images down to 150 px maximum. This is so you don't have to fiddle around too much with resizing your images exactly, then uploading them someplace to link to them, etc. This is to make your life easier.
However, we've noticed some people are linking to MASSIVE images. This is one of the reasons why the forum is running so slow. Please shrink them down to at most 300px, ideally 150px. If the problem persists we will simply put a lock on images at 150px, and everybody who isn't at that size or smaller will see a big red x where their avatar should be.