Not sure how feathers works but I once wrote my own list and it could handle millions of items if required without breaking a sweat.
It just had x number of list items enough to fill the viewable area + 1.
Then just updated the contents dynamically.
So a list 20 items tall had 21 items in it so it could scroll seamlessly.
That way the amount of data has no impact on rendering cost. You only ever update at most x + 1 number of renderables where x is the number of items that fit in the list view.
Just looked at Josh's link. Sums it up perfectly 😃