>>> (setq Man-width 75)
>>
>> Emacs nowadays calculates the width dynamically, depending on the
>> dimensions of the window.
>
> Why not make Emacs dynamically size it's windows to the width of the
> display first? ;~O

Implementing this in bug#32536 revealed that mouse drag events become
too laggy when calling Man-update-manpage after every drag event on the
window separator.  JavaScript libraries provide a good solution that makes
web UI more responsible, see https://duckduckgo.com/?q=javascript+debounce

It could be good to have analogous in Emacs to e.g. make window resizing
more responsible.  So instead of

(add-hook 'window-size-change-functions 'Man-window-size-change)

in Man-mode this patch will allow

(add-hook 'window-size-change-functions (debounce 'Man-window-size-change 2))

where the last arg means 2 seconds sliding window to wait, and make the
final call once there are no more resizing events during that time period.

Since its args are similar to the args of run-with-timer, it makes sense
to add it to timer.el: