[development] The router and links tables split - what caused it?

[robert crowther]

Yes, I know they split (Drupal 6, was it?). I seem to remember reading
somewhere in code, or near code, documentation that this was not simply
for clarity or encapsulation, but performance.

If I recall the comment alright, does anyone know what that performance
issue was? Were people running, say, college sites, or auction sites,
and finding they were bloating the links tables? A more general question
- what was the scale of the bloating that caused a database to slow
down?

Answers to these questions may have a direct impact on the development
of my module,

 http://drupal.org/project/taxonomy_treemenu

In response to user discussion I'm considering a complete re-write of
the links code.

Rob