Eli Zaretskii <eliz@gnu.org> writes:

>> There are some easy things that can be done to improve `file-truename'
>> performance somewhat. For example, the number of calls to
>> `file-name-nondirectory' can be trivially reduced in the `file-truename'
>> code - it is called up to three times in a row.
>> 
>> (see my earlier message in https://yhetil.org/emacs-bugs/87jzlmd831.fsf@localhost/)
>> 
>> Will it be of interest?
>
> Yes, of course.  Those kinds of changes are no-brainers, really.

See the attached patch.