Congrats, Mike ...
It would be interesting to see the benchmark with a helper (single) recursive function :
(defun fibo* ( a b x)
(if (= x 0) a
(fibo* b (+ a b) (1- x))))
(defun fibo (x)
(fibo* 1 1 x))
;; needs to be converted into Scheme syntax
-------------------------------------------output from the REPL , CLisp in interpreted mode :
[4]> (time (fibo 35))
Real time: 0.0 sec.
Run time: 0.0 sec.
Space: 12 Bytes
14930352
[5]> (time (fibo 350))
Real time: 0.0 sec.
Run time: 0.0 sec.
Space: 8496 Bytes
10119911756749018713965376799211044556615579094364594923736162239653346274
[6]>
[6]> (time (fibo 3500))
Real time: 0.046875 sec.
Run time: 0.046875 sec.
Space: 566808 Bytes
GC: 1, GC time: 0.03125 sec.
2071302422030262753416199537299341464207691967344600973326088247223853841292493160797697343340451944
4976593116933291600999770493153188194487391358228695151342468224877086896425368422810438268966043143
5922397519756497357499967505758679688646649075302803539077528386858224498222588856280163988716395494
3851743918399601630391772093506274643901267107805198009064692093234224193403702061606850299426651476
9908089454731212877225205687361987022780519210425124250789022062818138048190207921943410932369612123
1264625722768733484440412902313033879037929246974105582008193813127877888969955929338924710176760096
4317826621273936149422080698086653588915837724060010304084595878920010121852066682093621607829876763
92635512259975382189797347146626
[9]> (compile 'fibo) (compile 'fibo*) ;; switched to compiled code
NIL ;
NIL
[10]> (time (fibo 3500))
Real time: 0.0 sec.
Run time: 0.0 sec.
Space: 566808 Bytes
2071302422030262753416199537299341464207691967344600973326088247223853841292493160797697343340451944
4976593116933291600999770493153188194487391358228695151342468224877086896425368422810438268966043143
5922397519756497357499967505758679688646649075302803539077528386858224498222588856280163988716395494
3851743918399601630391772093506274643901267107805198009064692093234224193403702061606850299426651476
9908089454731212877225205687361987022780519210425124250789022062818138048190207921943410932369612123
1264625722768733484440412902313033879037929246974105582008193813127877888969955929338924710176760096
4317826621273936149422080698086653588915837724060010304084595878920010121852066682093621607829876763
92635512259975382189797347146626
[11]>
-------------------------------------------------------------------------------------------
best Rob