[development] Tuning your server for optimal Drupal performance

[Moshe Weitzman]

  > path.module is costly in 4.6 if you have several hand added aliases
> (like we had on a site for every node of a certain type). Grabbing the
> whole list of aliases into memory, then getting and returning the array
> on *every* call to the get_normal_path, and flipping the array on *every
> call* to this function is extremely costly! The fact that pathauto is
> costly is because path.module is costly itself with a lot of aliases.
> Pathauto only helps you to quickly have these enourmous number of aliases.

all this is right, but path.module is not at fault. this path machinery 
works with path.module disabled. path.module is just a UI to manage the 
url_alias table.