Some tables are preceded by a empty div.content-table-right and div.content-table-left with a high height. This height increases immensely when the size of the viewport changes (i.e. opening the developer tools or changing the window size). It's easily possible to get the height to tens of millions, which is more than Firefox can handle (unable to scroll to the end of the page).
Customize query in gerrit
|mediawiki/skins/Timeless||master||+10 -7||Make giant table sticky captions js only affect giant tables|