bug#3219: Long Line Sluggishness

bug#3219: Long Line Sluggishness

[David Reitter]

Emacs becomes extremely sluggish when long lines are used.

To reproduce:
Emacs -Q
Enter long line through recursive copy/paste  (about 700k characters  
in my example)
- use vertical scrollbar to scroll to the bottom   -> doesn't work
- use End key to scroll to bottom

Now move around, enter text, scroll up, etc: everything happens with a  
substantial (0.5-1.0 seconds) delay.

For a more practical example: I was working in lisp-interaction-mode,  
typing C-j after "load-history", and expanding one of the "..."  
ellipses. This gave me a line in excess of 100k.

Similarly, users might want to edit long (mostly binary) files.  But  
maybe that's a corner case, and it would be okay to change C-j a bit  
to format the output better.

This is not a regression compared to Emacs 22 (comparing to Carbon  
port).




In GNU Emacs 23.0.92.19 (i386-apple-darwin9.6.0, NS apple-appkit-949.43)
  of 2009-04-30 on SCARLETT.PSY.CMU.EDU
Windowing system distributor `Apple', version 10.3.949
configured using `configure  '--with-ns' '--without-x' 'CFLAGS=- 
DMAC_OS_X_VERSION_MIN_REQUIRED=1040  -O3''

Important settings:
   value of $LC_ALL: nil
   value of $LC_COLLATE: en_US.US-ASCII
   value of $LC_CTYPE: en_US.US-ASCII
   value of $LC_MESSAGES: en_US.US-ASCII
   value of $LC_MONETARY: en_US.US-ASCII
   value of $LC_NUMERIC: en_US.US-ASCII
   value of $LC_TIME: en_US.US-ASCII
   value of $LANG: en_US.UTF-8
   value of $XMODIFIERS: nil
   locale-coding-system: us-ascii-unix
   default-enable-multibyte-characters: t

Major mode: Lisp Interaction

Minor modes in effect:
   tooltip-mode: t
   mouse-wheel-mode: t
   menu-bar-mode: t
   file-name-shadow-mode: t
   global-font-lock-mode: t
   font-lock-mode: t
   global-auto-composition-mode: t
   auto-composition-mode: t
   auto-encryption-mode: t
   auto-compression-mode: t
   line-number-mode: t
   transient-mark-mode: t

Recent input:
s-v s-v s-v s-v s-v s-v s-v s-v s-v s-v <wheel-up>
<double-wheel-up> <triple-wheel-up> <triple-wheel-up>
<wheel-up> <double-wheel-up> <triple-wheel-up> <triple-wheel-up>
<triple-wheel-up> s-a s-c <wheel-down> <double-wheel-down>
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down>
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down>
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down>
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down>
<triple-wheel-down> <triple-wheel-down> <triple-wheel-down>
<triple-wheel-down> <triple-wheel-down> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<mouse-1> C-SPC <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <down-mouse-1> <down-mouse-1> <down-mouse-1>
<down-mouse-1> <mouse-1> <end> s-c SPC s-v SPC s-v
SPC s-v s-v s-v s-v s-v s-v s-v <wheel-up> <double-wheel-up>
<wheel-up> <double-wheel-up> <down-mouse-1> <mouse-1>
<down-mouse-1> <mouse-1> <down-mouse-1> <mouse-1> <down-mouse-1>
<mouse-1> <down-mouse-1> <mouse-1> <down-mouse-1> <mouse-1>
<wheel-up> <double-wheel-up> <wheel-up> <double-wheel-up>
<wheel-up> <double-wheel-up> <escape> x r e p o r t
- b <tab> <return>

Recent messages:
byte-code: Beginning of buffer [5 times]
byte-code: End of buffer [5 times]
byte-code: Beginning of buffer [4 times]
byte-code: End of buffer [6 times]
Mark set [114 times]
Saved text until "lled through super interpretKeyEvents:])"
byte-code: End of buffer
Mark set [2 times]
Saved text from "per interpretKeyEvents:]) <NSTextInput> "
Mark set [9 times]

bug#40007: 28.0.50; Emacs gets very slow when displaying a long line

[Lars Ingebrigtsen]

David Reitter <david.reitter@gmail.com> writes:

> Emacs becomes extremely sluggish when long lines are used.

These issues have been fixed in Emacs 29 -- long lines no longer slows
down Emacs (to these degrees), so I'm closing this bug report.

There may be issues remaining with long lines, and if so, please open
new bug reports for those issues (and cases for reproduction would be
appreciated).