Subject: Re: bug#17831: 24.4.50; bad default value for `Man-width'

From: Juri Linkov <[email-masked]>
Date: Sat, 28 Jun 2014 02:45:59 +0300

>> Could it be possible that a slowdown is caused by `narrow-to-region'?
>
> `narrow-to-region' is cheap.  But doing it by chunks is necessarily
> slower, because there is a non-negligible overhead "per chunk".
> `narrow-to-region' is part of that overhead, but there are others much
> more costly, such as going through redisplay (which may even sometimes
> have to update some part of the display, such as the "nn%" thingy since
> that depends on the total buffer size).

If it's not possible to increase the default chunk size to call
process-filter less often (e.g. now for `M-x man RET bash' it's called
90 times), then some users might want to disable this using a new option
like `Man-sync'.  OTOH, since most of man pages are much smaller,
maybe this is not a problem.

But still the users need an indication that the formatting
is not finished.  grep/compilation and vc display a string
like "waiting..." or "compiling..." in the mode-line, so
man.el could display in the mode-line "formatting..."