Subject: Very bad/slow redraw with vertical split.

From: Robin Lee Powell <[email-masked]>
Date: Thu, 23 Oct 2008 19:54:28 -0700

I'm playing around with vertical split.  I'm using Screen version
4.00.03jw4 (FAU) 2-May-06 on Debian.

When I have vertical split on, less is slow.  *Really* slow.  So is
more.  vim is OK.  When I say "slow", I mean that when I say "less
file", it takes ~20 seconds for it to put the first screenful of
data up.

Any idea what's up?

-Robin

-- 
They say:  "The first AIs will be built by the military as weapons."
And I'm thinking:  "Does it even occur to you to try for something
other than the default outcome?" -- http://shorl.com/tydruhedufogre
http://www.digitalkingdom.org/~rlpowell/ *** http://www.lojban.org/

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From: "Thomas Adam" <[email-masked]>
Date: Fri, 24 Oct 2008 14:26:30 +0100

Hello --

> file", it takes ~20 seconds for it to put the first screenful of

It's a known caveat of vertical splits in screen.  Screen has to
continually redraw the region and so that slows things down.

-- Thomas Adam

---

From: Robin Lee Powell <[email-masked]>
Date: Fri, 24 Oct 2008 11:34:16 -0700

On Fri, Oct 24, 2008 at 02:26:30PM +0100, Thomas Adam wrote:
> > I'm playing around with vertical split.  I'm using Screen
> > version 4.00.03jw4 (FAU) 2-May-06 on Debian.
> >
> > When I have vertical split on, less is slow.  *Really* slow.  So
> > is more.  vim is OK.  When I say "slow", I mean that when I say
> > "less file", it takes ~20 seconds for it to put the first
> > screenful of data up.
> >
> > Any idea what's up?
> 

I had a giant post written about how vertical splits in emacs and
vim are quite fast, and how running vim under a vertical split in
screen is also snappy, as opposed to running less, so there *must*
be a problem somewhere...

And then I realized that when you page down in vim, it redraws its
display area once.  When you page down in less, it redraws line by
line.

-_-

Holding down j in vim to make it redraw line by line makes
everything just as slow as less.

So.

Can anyone reccomend a less (ha!) stupid pager?  more does the same
thing, and I can't view man pages like this.

less -c mostly does the trick...  Except that the initial screen
clear to put the cursor at the top line is done the slow way, and
hence takes ~30 seconds.  "clear ; less -c [file]" works, but I'd
love a better suggestion.

-Robin

---

From: "Tom Scogland" <[email-masked]>
Date: Fri, 24 Oct 2008 15:26:14 -0400

Actually I use vim for that these days.  I have an alias that starts vim and
runs ":Man <arguments>"  whenever I run man.  That means it works nice and
fast, and I get nicely highlighted man pages.  As to a less stupid dedicated
pager, there's always most, which also does syntax highlighting though the
key commands don't quite work for me.  It might do the redraw a little
better, but I'm not sure.

-- 
-N
AKA:Tom Scogland
I am enough of an artist to draw freely upon my imagination. Imagination is
more important than knowledge. Knowledge is limited. Imagination encircles
the world.
-Albert Einstein
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From: Robin Lee Powell <[email-masked]>
Date: Fri, 24 Oct 2008 13:00:40 -0700

Yes, most does the right thing.  Thanks!

"view" (which is just read-only vim) does as well.

-Robin

On Fri, Oct 24, 2008 at 03:26:14PM -0400, Tom Scogland wrote:
> Actually I use vim for that these days.  I have an alias that
> starts vim and runs ":Man <arguments>"  whenever I run man.  That
> means it works nice and fast, and I get nicely highlighted man
> pages.  As to a less stupid dedicated pager, there's always most,
> which also does syntax highlighting though the key commands don't
> quite work for me.  It might do the redraw a little better, but
> I'm not sure.
>

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From: [email-masked] (Trent W. Buck)
Date: Sat, 25 Oct 2008 11:15:22 +1100

Robin Lee Powell

> display area once.  When you page down in less, it redraws line by

Please report this bug to the less maintainer.

> love a better suggestion.

Does this work?  It seems faster to me, but I can't get a big enough
$COLUMNS on my 7" screen to get enough slowdown to see it disappear.

    sudo aptitude install w3m
    sudo update-alternatives --set pager /usr/bin/w3m

---

From: [email-masked] (Trent W. Buck)
Date: Sat, 25 Oct 2008 11:19:11 +1100

"Tom Scogland" <[email-masked]> writes:

> Actually I use vim for that these days.  I have an alias that starts
> vim and runs ":Man <arguments>"  whenever I run man. 

For Emacs' M-x shell, I have this in .bashrc:

    if test -z "$EMACS$INSIDE_EMACS"
    then
        : [...]
    else
        PS1='$ '                   # be brief in M-x shell
        export PAGER=cat           # fuck you, git-log!
        if which man &>/dev/null
        then man () { twb-emacsclient -e "(man \"$1\" t)"; }
        else man () { twb-emacsclient -e "(woman \"$1\" t)"; }
        fi
        info () { twb-emacsclient -e "(info \"${2+(}$1${2+)$2}\")"; }
    fi