MAYBE

Initial complexity problem:
1:	T:
		(1, 1)    f300(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f1(v, w, x, y, z, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u)
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f1(a, b, c, d, e, f, g, 256, v, w, x, y, z, b1, c1, d1, q, r, s, t, u) [ a1 >= 1 /\ f + 1 = g /\ h = 256 ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f1(a, b, c, d, e, f, g, h, v, w, x, y, z, b1, c1, p, q, r, s, t, u) [ 0 >= h /\ f + 1 = g ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f1(a, b, c, d, e, f, g, h, v, w, x, y, z, b1, c1, d1, 256, r, s, t, u) [ a1 >= 1 /\ g >= f + 1 /\ g >= f + 2 /\ q = 256 ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f1(a, b, c, d, e, f, g, h, v, w, x, y, z, b1, c1, p, q, r, s, t, u) [ 0 >= q /\ g >= f + 1 /\ g >= f + 2 ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f2(a, b, c, d, e, f, g, h, v, w, k, l, m, n, o, p, q, 0, 0, 0, u) [ f >= g ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f3(a, b, c, d, e, f, g, h, v, w, x, y, z, b1, c1, d1, q, h, h, h, a1) [ h >= 1 /\ h >= 257 /\ f + 1 = g ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f3(a, b, c, d, e, f, g, h, v, w, x, y, z, b1, c1, d1, q, h, h, h, a1) [ h >= 1 /\ 255 >= h /\ f + 1 = g ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f3(a, b, c, d, e, f, g, h, v, w, x, y, z, b1, c1, d1, q, q, q, q, a1) [ q >= 1 /\ q >= 257 /\ g >= f + 1 /\ g >= f + 2 ]
		(?, 1)    f1(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u) -> f3(a, b, c, d, e, f, g, h, v, w, x, y, z, b1, c1, d1, q, q, q, q, a1) [ q >= 1 /\ 255 >= q /\ g >= f + 1 /\ g >= f + 2 ]
	start location:	f300
	leaf cost:	0

Slicing away variables that do not contribute to conditions from problem 1 leaves variables [f, g, h, q].
We thus obtain the following problem:
2:	T:
		(?, 1)    f1(f, g, h, q) -> f3(f, g, h, q) [ q >= 1 /\ 255 >= q /\ g >= f + 1 /\ g >= f + 2 ]
		(?, 1)    f1(f, g, h, q) -> f3(f, g, h, q) [ q >= 1 /\ q >= 257 /\ g >= f + 1 /\ g >= f + 2 ]
		(?, 1)    f1(f, g, h, q) -> f3(f, g, h, q) [ h >= 1 /\ 255 >= h /\ f + 1 = g ]
		(?, 1)    f1(f, g, h, q) -> f3(f, g, h, q) [ h >= 1 /\ h >= 257 /\ f + 1 = g ]
		(?, 1)    f1(f, g, h, q) -> f2(f, g, h, q) [ f >= g ]
		(?, 1)    f1(f, g, h, q) -> f1(f, g, h, q) [ 0 >= q /\ g >= f + 1 /\ g >= f + 2 ]
		(?, 1)    f1(f, g, h, q) -> f1(f, g, h, 256) [ a1 >= 1 /\ g >= f + 1 /\ g >= f + 2 /\ q = 256 ]
		(?, 1)    f1(f, g, h, q) -> f1(f, g, h, q) [ 0 >= h /\ f + 1 = g ]
		(?, 1)    f1(f, g, h, q) -> f1(f, g, 256, q) [ a1 >= 1 /\ f + 1 = g /\ h = 256 ]
		(1, 1)    f300(f, g, h, q) -> f1(f, g, h, q)
	start location:	f300
	leaf cost:	0

Repeatedly removing leaves of the complexity graph in problem 2 produces the following problem:
3:	T:
		(?, 1)    f1(f, g, h, q) -> f1(f, g, h, q) [ 0 >= q /\ g >= f + 1 /\ g >= f + 2 ]
		(?, 1)    f1(f, g, h, q) -> f1(f, g, h, 256) [ a1 >= 1 /\ g >= f + 1 /\ g >= f + 2 /\ q = 256 ]
		(?, 1)    f1(f, g, h, q) -> f1(f, g, h, q) [ 0 >= h /\ f + 1 = g ]
		(?, 1)    f1(f, g, h, q) -> f1(f, g, 256, q) [ a1 >= 1 /\ f + 1 = g /\ h = 256 ]
		(1, 1)    f300(f, g, h, q) -> f1(f, g, h, q)
	start location:	f300
	leaf cost:	5

Complexity upper bound ?

Time: 0.329 sec (SMT: 0.306 sec)