2) the use of an old implementation; for instance, the references in the following two sections (Rete II and Rete-NT) compare some commercial products to totally outdated versions of CLIPS and they claim that the commercial products may be orders of magnitude faster than CLIPS; this is forgetting that CLIPS 6.30 (with the introduction of hash tables as in Rete II) is orders of magnitude faster than the version used for the comparisons (CLIPS 6.04).
