I have a question about this, namely: how to make a line the 'window start'?
Using 'set-window-start` does not work.

From 'emacs -Q' (which starts within the scratch buffer),
immediately evaluate

(set-window-start nil (point))

to set the 'new' window start. Subsequently do

(set-window-vscroll nil 1)

it will scroll from the start of the buffer, and not from the 'new' window
start
as I would expect
(of course, here there are no lines after the 'new' window start, but you
could
insert 1 to 3 on separate lines then set the line with 1 to window start,
but this
does not really change anything).


On Tue, 26 Apr 2022 at 14:49, Po Lu <luangruo@yahoo.com> wrote:

> dalanicolai <dalanicolai@gmail.com> writes:
>
> > So I have created `image-roll.el` for displaying documents/books (see
> > here).  However, I have just noticed that it uses a large amount of
> > RAM when viewing (or trying to) pages in the back of 'large'
> > books. But even if RAM usage still looks perfectly fine, Emacs crashes
> > when trying to scroll to higher page numbers.
>
> I didn't try to reproduce this problem, but note that it's slow to
> vscroll large amounts of text.  Instead, find the start of the first
> line that will be visible onscreen (using window-text-pixel-size or
> posn-at-point), make that the window start, and set vscroll starting
> from there instead.
>