YES

(format LCTRS :logic QF_LIA)
(fun fastfib 1 :sort (Int Int))
(fun g 1 :sort (Int Int))
(fun u 5 :sort (Int Int Int Int Int Int))
(fun v 5 :sort (Int Int Int Int Int Int))

(rule (g x_0) (g x_0) :vars ((x_0 Int)))
(rule (v x_1 i_2 p_3 q_4 z_5) p_3 :guard (>= i_2 x_1) :vars ((x_1 Int) (i_2 Int) (p_3 Int) (q_4 Int) (z_5 Int)))
(rule (v x_6 i_7 p_8 q_9 z_10) (v x_6 (+ i_7 1) (+ p_8 q_9) p_8 z_10) :guard (< i_7 x_6) :vars ((x_6 Int) (i_7 Int) (p_8 Int) (q_9 Int) (z_10 Int)))
(rule (u x_11 i_12 p_13 q_14 z_15) (v x_11 i_12 p_13 q_14 (g 0)) :guard (> x_11 1) :vars ((x_11 Int) (i_12 Int) (p_13 Int) (q_14 Int) (z_15 Int)))
(rule (u x_16 i_17 p_18 q_19 z_20) 1 :guard (= x_16 1) :vars ((x_16 Int) (i_17 Int) (p_18 Int) (q_19 Int) (z_20 Int)))
(rule (u x_21 i_22 p_23 q_24 z_25) 0 :guard (<= x_21 0) :vars ((x_21 Int) (i_22 Int) (p_23 Int) (q_24 Int) (z_25 Int)))
(rule (fastfib x_26) (u x_26 0 1 0 0) :vars ((x_26 Int)))

Confluent by Parallel Closedness with proof:
no critical pairs

Elapsed Time:  14.38 ms