from itertools import izip
from datetime import datetime
from maya import cmds

def slow_version(uvs):
    a = ['meshName.uvst[0].uvsp[*]']
    a_append = a.append
    for u, v in izip(uvs[0], uvs[1]):
        a_append(u)
        a_append(v)
    # a data for "cmds.setAttr(*a, type='float2')"

def fast_version(uvs):
    us, vs = uvs
    s_len = len(us)
    a = ['meshName.uvst[0].uvsp[*]'] + ([0] * (s_len * 2))
    def ud(i, u):
        a[i*2+1] = u
    def vd(i, v):
        a[i*2+2] = v
    (ud(i, u) for i, u in enumerate(us))
    (vd(i, v) for i, v in enumerate(vs))
    # a data for "cmds.setAttr(*a, type='float2')"

# Test data, Like a maya.api.OpenMaya.MFnMesh.getUVs return value.
uvs = [[0] * 100000000, [1] * 100000000]

start = datetime.now()
slow_version(uvs)
# My machine's output about 16 sec.
print('slow_version', str(datetime.now() - start))

start = datetime.now()
fast_version(uvs)
# My machine's output about 3 sec.
print('fast_version', str(datetime.now() - start))