title: Using Lisp (or AutoLisp) how good is the associative lists performance?
body: <p>I'm doing an AutoLisp project which uses long associative structures to do heavy geometrical processing - so I'm curious about the associative list intense use timing results.
  How simple/complex is the implementation? It uses some data structure or a normal list of dotted pairs?
  The are any extension for b-tree or something?</p>