> I suggest being very careful with this.  While it's a very nice feature,
> it's bound to be slow with large tables.  And it is very frustrating for
> users when typing becomes laggy.

The feature could be an optional minor mode first and then later made
default if it proves to work well in every situation.

With the techniques I suggested there should be no lag at all, because
for smaller tables emacs can handle automatic formatting instantly and
with bigger tables the code can introduce an automatic idle delay
(sit-for), so the automatic reformat will happen only when the user is
idle for a short while. The idle period length can depend on the size
and complexity of the table.