Originally Posted by cliffordk

i've had this happen a lot on the phone, less often on the computer.

I've attributed it to inline advertisements. So, the text will load pretty quickly, but then the system keeps jumping around to the ads as they continue to load.
@jppe mentioned photo pages, or photo heavy pages.

This likely has to do with as photos are slowly loaded, the cursor absolute position stays the same while the length of page varies.

It may be a browser problem with how they're dealing with cursor position. But, another option would be for the system to rapidly review photo sizes (and the current window size/zoom), and open a blank box for images to open into. Thus the cursor doesn't jump.