Page up and down keys skip several lines in a review

When navigating a file using the Page Up and Page Down keys, several lines are skipped. For example, when viewing a file and the last line displayed is 81, after hitting page down, the first line is 87, which skips several lines.

The j/k shortcuts are not sufficient as they are used to navigate between elements and if the element is larger than the the window height, then key parts are missed when using page up and down.