bug#44983: Truncate long lines of grep output

[Eli Zaretskii]

> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Tue, 1 Dec 2020 17:02:09 +0200
> 
> >>> This is a bug problem - often grep output lines are so long
> >>> that Emacs freezes, so need to kill the process.  Updating
> >>> manually ignored-files every time a new file causes freeze
> >>> is very unreliable and time-consuming workaround.
> >>
> >> And a non-obvious one (for an average user).
> >>
> >> Is the same problem exhibited by commands using the Xref UI? I don't
> >> remember seeing it, but of course our projects can be very different.
> > 
> > No difference from grep, Xref output has the same problem.
> 
> Perhaps (setq truncate-lines t) could help in that case?

Not necessarily, because the truncated parts are still in the buffer,
and the display code which is slow in that case basically moves
through the buffer one character at a time in many cases.  Only some
specific scenarios (read: a small number of commands) can jump to the
next physical line disregarding the truncated parts.