;; If range is at least 20% dense, use vector mapping. Crossover
;; point solely on basis of space would be 25%. Vector mapping
;; is always faster, so give the benefit of the doubt.
;; If range is at least 20% dense, use vector mapping. Crossover
;; point solely on basis of space would be 25%. Vector mapping
;; is always faster, so give the benefit of the doubt.