Just a week ago I made the startling discovery that FB's mobile web app it's actually worse than a lot of websites I used to visit at the end of the 90s - early 2000 on Netscape 4.

Case in point, their textarea thingie for when you're writing a message to someone: after each letter push there is an actual, very discernible lag until said letter shows up in the textarea field. So much so that there are cases when I'd finished typing an entire word before it shows up on my mobile phone's screen. I suspect it's something related to the JS framework they're using (a plain HTML textarea field with no JS attached works just fine on other websites, like on HN), maybe they're doing an AJAX call after each key-press (?!), I wouldn't know. Whatever it is, it makes their web messenger almost unusable. (if it matters, I'm using an iPhone4).