It does, yes. I didn't think it would be a problem (keep in mind that most pictures won't be quite as huge and will load considerably faster). This could be solved by making the images load with the width limit already in place.
A consequence of that would be that if you were to load the thread with no javascript support, you would always see the images scaled down without an easy way of scaling them back up. The way I have it set up, if you view the thread with no JS, you will see all images in their full size (i.e. no difference from how things were in the past). If people feel that having it the other way around would be better, that's a very easy fix.
EDIT: Actually, it won't be that hard to get the best of both words. I'll fix it soon.