Try a more efficient unification algorithm such as those described in "An Efficient Unification Algorithm" by Martelli, "A practically efficient and almost linear unification algorithm" by Escalada-Imaz, "A Practically Linear Unification Algorithm" by Baxter.
Try a more efficient unification algorithm such as those described in "An Efficient Unification Algorithm" by Martelli, "A practically efficient and almost linear unification algorithm" by Escalada-Imaz, "A Practically Linear Unification Algorithm" by Baxter.