Two things that made scrolling back feel like work.
The jump-to-newest button animated. An animated scroll travels the whole
transcript, so the further back somebody has read the longer the press
takes -- the one control whose cost grows with how much there is to
skip, which is backwards. It goes straight there now.
History loaded a page per gesture, and a page is eighty *events*. Eighty
events are routinely one row: a reply arrives as hundreds of text deltas
that fold into a single message. So a page could land and leave the far
end exactly where it was -- and since the far end moving is what asks
for the next page, nothing did. The list then only loaded when somebody
dragged it again, which is what "it only loads when you touch the top"
was. It now keeps fetching until there are rows behind the reader again,
and starts doing that a cushion before the end rather than at it.
Measured on a session of five very long replies, about two thousand
events: reaching the oldest message used to stall at every drag; it now
takes flings alone, and the jump back to the newest end is one frame.
iris
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