a + b + c
"".join((a, b, c))
"%s%s%s" % (a, b, c)
"{}{}{}".format(a, b, c)
f"{a}{b}{c}"
c="";c+=x;c+=y;c+=z;c

from timeit import timeit
from typing import Dict, Tuple

V = (
    'x + y + z',
    '"".join((x, y, z))',
    '"%s%s%s" % (x, y, z)',
    '"{}{}{}".format(x, y, z)',
    'f"{x}{y}{z}"',
    'c="";c+=x;c+=y;c+=z;c'
)
B = (0, 4, 8, 10, 12, 16)
S = [1 << b for b in B]
T: Dict[str, Dict[int, Tuple[float, float]]] = {}

for size in S:
    x, y, z = (c * size for c in "xyz")
    var = dict(V=V, x=x, y=y, z=z)
    print(f"size={size}")
    times = sorted((timeit(v, number=1000000, globals=var), v) for v in V)
    for (d, v) in times:
        rel = 100 * (d / times[0][0] - 1)
        print(f"\t{d:.3f}\t+{rel:3.0f}%\t{v:s}")
        T.setdefault(v, {})[size] = (d, rel)

for v, s in T.items():
    row = ' | '.join(
        f"{d:.3f} +{rel:3.0f}%"
        for (d, rel) in (s[size] for size in S)
    )
    print(f"| `{v:24s}` | {row} |")