bug#51523: 29.0.50; gnus-mime-view-part-externally very slow

[Gregory Heytings]

> > * lisp/net/mailcap.el (mailcap-mime-info): Remove force argument to 
> > mailcap-parse-mailcaps.  Fixes bug#51523.
>
> The mailcaps are being parsed on each invocation on purpose to catch 
> edits.
>
> The problem here is that it takes a long time to parse the file(s) -- it 
> should be pretty much instantaneous.

Hmm...  On my computer, Stefan's recipe (benchmark-run 1 (mapcar 
#'mailcap-mime-info (mailcap-mime-types))) takes 0.5 s without the force 
argument, and 25 s with it.

FWIW, on my computer (Debian bookworm):

(length (mailcap-mime-types)) => 1478
(benchmark-run 1 (mailcap-mime-info "application/octet-stream")) => 
(0.073829567 1 0.02996454400000001)
(benchmark-run 1 (find-auto-coding "/etc/mailcap" 4096)) => 
(0.00030021999999999997 0 0.0)
(benchmark-run 1 (mapcar #'mailcap-mime-info (mailcap-mime-types))) => 
(25.234923454 1674 12.865286990000001)