Re: address@hidden: Poor performance over DSL link]

[Richard Stallman]

Here is the old message.

From: "Kim F. Storm" <address@hidden>
To: address@hidden
CC: address@hidden, address@hidden, address@hidden
In-reply-to: <address@hidden> (message from Richard
        Stallman on Tue, 12 Dec 2000 09:02:15 -0700 (MST))
Subject: Re: Performance running emacs with X over 64 kbps link.
References: <address@hidden>
        <address@hidden>
        <address@hidden>
        <address@hidden> <address@hidden> <address@hidden>
Content-Type: text
Content-Length: 1997

> Date: Tue, 12 Dec 2000 09:02:15 -0700 (MST)
> From: Richard Stallman <address@hidden>
> 
>     Optimizing emacs' wire efficiency when using the X protocol may be
>     interesting but there are certainly many more important things to do...
> 
> I agree it is not of first-level importance.
> And it makes sense to tell people in this situation
> "Turn off features A, B and C for faster operation."
> 
> Still, it does matter to some extent.  It could be worth figuring out
> which features to advise them to turn off, and if something is
> gratuitously slow in how it uses X, speeding it up would be good for
> everyone.

I have been digging a little further into this issue.
I was wondering why emacs was so slow during start-up (+ 1 minute)
especially the noticeable delay between messages like
        Loading some-file.elc...
and
        Loading some-file.elc...done

It seemed that every package that uses 'defface' or 
actively manipulates the x-frame parameters are subject
to a several seconds load time.

I then used ethereal to trace on ppp0, and it turns out that emacs
is doing multiple calls to XListFonts(), XLookupColor() and
XAllocColor() - for the same font pattern and colors...

Since there is obviously no caching of the information read
from the X-server, it repeats those requests... which in
total causes a significant delay in emacs startup.

Totally, emacs exchanges ~1800 X11 (and TCP) packets
with the X-server before it is ready for use...  after some
75 seconds.  [this is when I delay the loading of .emacs
until the initial frame is properly displayed; without
that hack, loading emacs takes twice as long -- see my
previuos mails explaining this].

I don't know whether it is legal to cache any of this 
information, but doing so would probably make a significant
improvement in start-up time over slow links - any maybe
a small improvement in general.

-- 
Kim F. Storm  <address@hidden>      http://www.filanet.dk
Filanet Europe A/S    Herlev Hovedgade 82C,1 DK-2730 Herlev