[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#30457: 26.0.91; bidi-display-reordering makes navigation around melp
bug#30457: 26.0.91; bidi-display-reordering makes navigation around melpa/archive-contents slow
Wed, 14 Feb 2018 20:40:10 +0200
> From: Aaron Jensen <address@hidden>
> Date: Wed, 14 Feb 2018 08:49:58 -0800
> In this thread, Eli asked for a real world repro where
> bidi-display-reordering slows down emacs:
> I found that today, so I wanted to report it.
> Download: https://melpa.org/packages/archive-contents
> emacs -Q archive-contents
> Press and hold C-n (I have a very fast key repeat rate)
> On my machine, it takes about 13 seconds to get to the bottom of the
> window (where it first scrolls, not the bottom of the buffer, I don't
> have the patience for that).
> (setq bidi-display-reordering nil)
> Press and hold C-n
> On my machine, it takes about 1 second to get to the bottom of the
It's a 870K line with multi-level parentheses. As already mentioned
there, the BPA implementation that is part of the bidi reordering
makes this sluggish due to the many parentheses in such a long line.
(However, it's nowhere near 13 sec on my box. And going several lines
in one go, as in "C-u 20 C-n", makes it even faster.)
> I hope that this is a compelling enough use-case. I don't believe I have
> a use-case for it to be `t` right now, so I'll be setting it to `nil` by
> default in my config
Beware: the code which is used when bidi-display-reordering is nil is
unsupported since Emacs 24, so you are on your own when using it. I
urge you to reconsider.