Streaming follow scheduled a two-frame animation-frame chain per content
growth and then went through the list's programmatic scrollToEnd, whose
scroll bookkeeping schedules further frames. Together they roughly
doubled frame production for the whole stream (16 -> 35 frames/s in a
profiled streaming session), with the matching style recalc and layout
cost per frame.
In following-end mode, correct synchronously in the totalSize listener by
writing scrollTop directly — the same write path a user gesture takes —
and keep the animation-frame chain only for the anchored-turn glide.
Profiled streaming frame production returns to the previous engine's
range and peak heap drops from 164 MB to 90 MB.
Bohdan Triapitsyn
87c1ae809d