I'm trying to speed up computing terms of a simple recurrence where
the terms are computed modulo some value each iteration,

(defn NF-mod-limit [p q limit]
 (loop [n 0, nf 0, z 0, S 290797]
       (if (= n (inc q)) nf
        (recur (inc n)
               (mod (+ nf (* (mod S p) z)) limit)
               (mod (inc (* p z)) limit)
               (mod (* S S) 50515093))))))

So I added in some type hinting,

(defn NF-mod-limit [p q limit]
 (let [p (long p) q (long q) limit (long limit)]
 (loop [n (long 0), nf (long 0), z (long 0), S (long 290797)]
       (if (= n (inc q)) nf
        (recur (inc n)
               (long (mod (+ nf (* (long (mod S p)) z)) limit))
               (long (mod (inc (* p z)) limit))
               (long (mod (* S S) 50515093)))))))

But it doesn't run any faster.  Also it doesn't work without casting
to long within the recur.  Is that maybe a problem with mod and
primitive arithmetic or does this simply not speed up any more in
Clojure?

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