This occurs only when a read an email with links and between the links is normal text longer than the screensize.
What happens is when scrolling down from the beginning it's ok. But as soon as the 2nd link occurs on the screen (and the focus is switch to that link), the page is scrolling back to the beginning of the first link in one go. And i have to scroll down again. This time i can scroll further past that 2nd link (which is focussed).
The same happens when i scroll up and the focus changes back to the 1st link. It automatically scrolls down again from the 2nd link.