This is weird because it happens only on the Facebook profile page (definitely not on the main feed page).
The page becomes very sluggish in zen mode. Both scrolling down units (j) and scrolling the page (shift+j) is very slow. Observed that 'updateCUsAndRelatedState' is called twice every time you press 'j' or 'shift+j' in zen mode (ideally, the method shouldn't be called at all on scroll). Works fine when zen mode is off.
This does not happen on other sites (checked on StackOverflow, Twitter, Reddit, HN) or Facebook main page.
This is weird because it happens only on the Facebook profile page (definitely not on the main feed page).
The page becomes very sluggish in zen mode. Both scrolling down units (j) and scrolling the page (shift+j) is very slow. Observed that 'updateCUsAndRelatedState' is called twice every time you press 'j' or 'shift+j' in zen mode (ideally, the method shouldn't be called at all on scroll). Works fine when zen mode is off.
This does not happen on other sites (checked on StackOverflow, Twitter, Reddit, HN) or Facebook main page.