IRC, freenode, #hurd, 2011-05-07

<braunr> and as a last example: memory mapping is heavily used in the hurd,
  but for some reason, the map entries in an address space are still on a
  linked list
<braunr> a bare linked list
<braunr> which makes faults and page cache lookups even slower

A red-black tree was added to VM maps to speed up lookups.