On Mon, 06 Apr 2020 14:06:02 -0400
Stefan Monnier wrote:

>> @@ -299,7 +299,11 @@ unload-feature
>>                              ;; Known abnormal hooks etc.
>>  			    (memq x unload-feature-special-hooks)))
>>  	       (dolist (func removables)
>> -	         (remove-hook x func)))))
>> +	         (remove-hook x func)
>> +                 (save-current-buffer
>> +                   (dolist (buffer (buffer-list))
>> +                     (set-buffer buffer)
>> +                     (remove-hook x func t)))))))
>>            ;; Remove any feature-symbols from auto-mode-alist as well.
>>            (dolist (func removables)
>>              (setq auto-mode-alist
>
> Maybe instead of `(dolist (buffer (buffer-list))` within that big
> `mapatoms` within `(dolist (func removables)` (which is O(B*F*V) where
> B is the number of buffers, F is the number of functions and V is the
> number of hook vars), we should instead do it as:
>
>     (dolist (buffer (buffer-list))
>       (dolist (varvar (buffer-local-variables buffer))
                         ^^^^^^^^^^^^^^^^^^^^^^

Ha! Didn't know/think about that one, and indeed it makes a world of
difference. Thanks!

So I guess my defeatism will not prevail after all. Updated [2/3] attached.

-- 
Štěpán