That being said, giving a good estimation of page load time is downright impossible. You don't know in advance how many resources you need to load, you don't k

That being said, giving a good estimation of page load time is downright impossible. You don't know in advance how many resources you need to load, you don't know in advance how large they'll be, or how long the DNS reply will take ... If you don't want the scrollbar to move backwards, you can just give a rough approximation of progress, if any. And if you just wait until you certainly know how long it's going to be you're probably almost finished anyway. I guess there's a reason web browsers nowadays just use a little spinner that says »I'm doing ... uhm ... something!« instead of them pretending »I'm 46.5 % done«.