optimising "change CWD" algorithm in subshell mode

[Dmitry Smirnov]

On Tue, 6 Nov 2012 08:37:56 Egmont Koblinger wrote:
> I looked at the problem a while ago, and figured out that bash's speed
> improved quite a lot during versions, even though the latest is still not
> as fast as it should be, but much better than previous versions.  I figured
> out that with bash-4.2 the slowness it bearable and wasn't worth it for me
> to investigate any further.
>
> Dmitry, please make sure that you also use the newest bash.  If you're not,
> upgrading will perhaps significantly improve your experience.
> 

I'm not sure how much performance has increased comparing to older bash 
versions. At the moment I have bash_4.2.36 but I'm not too sensitive to this 
problem as I rarely explore deeply nested trees.

However I think even with up-to-date bash slowdown can be quite noticeable on 
older computers. Here is an example of feedback that I had difficulties to 
confirm until I went much deeper:

	http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=652883#30


> I'm really not sure about the crash, though.
> 

Crash is there, to reproduce just navigate deep enough and hide panels 
(Ctrl+O). I think we're all pretty much agree that fixing hangs/crashes are of 
much greater priority than optimising slowdown.

Cheers,
Dmitry.