Performance problems

Hi!

I'm having severe performance problems using LISA.  I tried to create
a very simple test case and it looks like this:

------------------------- file test.lisp -------------------------

(in-package :lisa-user)

(deftemplate foo () (slot foo))

(defvar *counter*)

(defun reset-counter ()
  (setq *counter* 0))

(defun make-foo-fact ()
  (assert-instance (make-instance 'foo
                      :foo (incf *counter*))))

(defrule rule-1 ()
  (foo (foo ?x))
  (foo (foo ?y))
  (foo (foo ?z))
  =>
  (print 'yo))

(defun test (&optional (n 10))
  (reset)
  (reset-counter)
  (dotimes (i n)
    (make-foo-fact)))

------------------------- file test.lisp -------------------------

Compile and load the code above and then TIME calls like (TEST 10),
(TEST 20), and so on.  On my machine I get the following results

  TEST 10:  0.020 s
  TEST 20:  0.660 s
  TEST 30:  4.596 s
  TEST 40: 91.741 s

which clearly demonstrate a hefty exponential growth.  This is with
LISA from CVS on LWW 4.4.6 but I've seen similar results when I
double-checked on Linux with CMUCL.

Clearly, my actual rules and facts are more complicated, but they show
similar symptoms.  Actually, it's even worse.

Is this expected behaviour or a bug?  Or am I doing something wrong?

Thanks,
Edi.


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