the sites could implement their own search to make it all work if they wanted to. they just dont. but blaming virtualization is not tit.
Browsers can easily render and scroll through entire wads of content.
The problem is, when the "line" comprising an email in the email list of Outlook Web is in a maze of (literally, just looked it up) about 30 divs deep, performance inevitably goes down the drain.
Computers in the 00s could handle inboxes with thousands of emails just fine and scroll through them. Outlook struggles keeping more than 30 in active memory. That's gotta be a joke.
By the way: the solution is rendering tabular stuff in, well, tables instead of armies of divs that try to be tables. That case has been optimized to death because that is how websites and applications used to be built.
The irony is that obsessing over smoothness and frames per second is what causes this in the first place.