The gain is that the author has at edit time full
control over where the
link points to. With runtime lookup a link might change because a certain
term was added to a certain namespace.
-- Jan Hidders
Well, that's not a bug but a feature! The term will not be added
to a certain namespace if there isn't already some disrepancy
(and if the author means the other subject he will surely link
to it explicitly, like [[Root (Botanics)]]) By doing the linking
in runtime we could make sure that all links point at their
most updated targets, which is an advantage. This is similar
to the reason why we use redirects.
As to runtime performance concerns, I'm sure that caching and/or
an optimised parser could do wonders in the Wikipedia case.
Wiki markup is _very light_.
Sincerely yours,
Uri Yanover