bug#41200: Displaying a tooltip with x-show-tip gets very slow as more faces are defined

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: cpitclaudel@gmail.com,  41200@debbugs.gnu.org
> Date: Sun, 24 May 2020 01:47:28 +0300
> 
> > Actually, the problem with the tab-line face will probably need to be
> > fixed on emacs-27.
> 
> I don't recommend using the trick with nconc in emacs-27.  It would be
> less risky if Clément will just move tab faces to faces.el in emacs-27.

Agreed.

> Or may I suggest to preload tab-line.el in emacs-27?

Doesn't sound justified to me.  I don't expect this feature to be so
popular as to always have it available.