so-long-mode and line-move-visual

[Eli Zaretskii]

Phil,

so-long.el has this passage:

 (defcustom so-long-variable-overrides
   '((bidi-inhibit-bpa . t)
     (bidi-paragraph-direction . left-to-right)
     (buffer-read-only . t)
     (global-hl-line-mode . nil)
     (line-move-visual . t)
     (show-paren-mode . nil)
     (truncate-lines . nil)
     (which-func-mode . nil))
   "Variables to override, and the values to override them with.

 The variables are given buffer-local values.  By default this happens if
 `so-long-action' is set to either `so-long-mode' or `so-long-minor-mode'.

 If `so-long-revert' is subsequently invoked, then the variables are restored
 to their original states.

 The combination of `line-move-visual' (enabled) and `truncate-lines' (disabled)
 is important for maximising responsiveness when moving vertically within an
 extremely long line, as otherwise the full length of the line may need to be
 scanned to find the next position.

It looks to me that the last paragraph (and the overrides to go with
it) has it backwards: line-move-visual set to nil produces _better_
performance than a non-nil value, and if truncate-lines is turned on,
the boost is even larger.  the explanation why is that so is correct,
but it describes the situation that's the opposite of the settings we
recommend.  I wonder why and how we came to the conclusion recorded in
the current code and the doc string.

Or what am I missing?