Создать хэш-таблицу изначально большого размера.

(defparameter *my-hash* (make-hash-table :size 100000))
; *MY-HASH*
(hash-table-size *my-hash*)
; 100000
(time (dotimes (n 100000) (setf (gethash n *my-hash*) n)))
; Compiling LAMBDA NIL: 
; Compiling Top-Level Form: 
; 
; Evaluation took:
;   0.04 seconds of real time
;   0.04 seconds of user run time
;   0.0 seconds of system run time
;   0 page faults and
;   0 bytes consed.
; NIL