22.1.50; insert-file-contents is slow under tramp

[Stephen Berman]

1. emacs -Q

2. I type C-x d and at the prompt type "/localhost:/ RET" and when
prompted type my user password and then complete the path to some
directory that contains a fairly large file (> 1MB is enough to
clearly show the problem), e.g. the lisp directory of the Emacs
sources.

3. I put the cursor on a large file, e.g. ChangeLog.12 (1251246 bytes)
and press RET.  On my machine it takes ~20 seconds for the buffer
visiting this file to appear and during that time emacs is consuming
almost 100% CPU.

If at step 2 I directly enter the path to the lisp directory of the
Emacs sources, avoiding tramp, and then do step 3, the buffer appears
almost instantly, as usual.  So the slowdown is only with tramp (also
if I use a different user, e.g. with /su::/, which is how I first
encountered the problem).  The slowdown seems to be proportional to
the size of the file, so not too long (but noticeable) with small
files.

Using edebug I found the slowdown occurs when insert-file-contents is
called in find-file-noselect-1.  I don't know how to debug it further.
This slowdown did not exist in my previous Emacs build from 2007-06-30.


In GNU Emacs 22.1.50.7 (i686-pc-linux-gnu, GTK+ Version 2.10.6)
 of 2007-08-21 on escher
Windowing system distributor `The X.Org Foundation', version 11.0.70199902
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Major mode: Group

Minor modes in effect:
  gnus-agent-mode: t
  shell-dirtrack-mode: t
  gnus-topic-mode: t
  gnus-undo-mode: t
  tabbar-mwheel-mode: t
  tabbar-mode: t
  recentf-mode: t
  display-time-mode: t
  show-paren-mode: t
  tooltip-mode: t
  tool-bar-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  temp-buffer-resize-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: identity

Recent input:
<return> e s <tab> <backspace> r <tab> s <tab> c v 
<tab> e <tab> / l i <tab> <M-backspace> l i s <tab> 
<return> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <return> <help-echo> 
<help-echo> <help-echo> <help-echo> <help-echo> <help-echo> 
<tool-bar> <kill-buffer> <tool-bar> <kill-buffer> C-c 
j m a <tab> <return> <up> <up> <up> <up> <up> <up> 
/ o 5 0 0 <return> <home> C-s t r a m C-w C-s C-s C-a 
<down> <down> <down> C-s C-s C-r C-r <left> SPC <up> 
SPC <f1> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <down> <down> <down> <down> <down> <down> <down> 
<down> <up> SPC <f1> <down-mouse-1> <mouse-2> <select-window> 
<select-window> <help-echo> <f1> <down> q M-x r e p 
o <tab> r <tab> b <tab> <return>

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