bug#27097: Combining Guix, direnv and Emacs for environment customisation

[Roel Janssen]

Ludovic Courtès writes:

> I agree that we could do a lot more things with a faster ‘guix
> environment’.  My guess is that it won’t be easy to go optimize, and
> very hard to go below 1 second.  We should profile that and see what can
> be done.

FWIW, on our NFS-mounted /gnu, the 'guix environment' command takes at
least 20 seconds, but for any reasonably big environment it takes more
than one minute.  The biggest bottleneck here is the disk latency.
Could it be that 'guix environment' accesses many files?  If we could
reduce that, it would speed things up (at least for us ;)).

Kind regards,
Roel Janssen