import bpy
import timeit

def get_active_layers():
    for area in bpy.context.screen.areas:
        if area.type == "VIEW_3D":
            v3d = area.regions.data.spaces.active
            break
    layers = []
    for x in range(20):
        if v3d.layers[x] is True:
            layers.extend([x])
    return layers

def test1():
    layers = get_active_layers()
    objlist = bpy.context.scene.objects
    for myobj in objlist:
        if myobj.hide is False:
            if 'MeasureGenerator' in myobj:
                # verify visible layer
                for x in range(0, 20):
                    if myobj.layers[x] is True and x in layers:
                        op = myobj.MeasureGenerator[0]
                        #draw_segments(context, myobj, op, region, rv3d)
                        break

def test2():
    layers = get_active_layers()
    objlist = bpy.context.scene.objects
    for myobj in objlist:
        if myobj.hide is False:
            if 'MeasureGenerator' in myobj:
                # verify visible layer
                for x in range(0, 20):
                    if myobj.layers[x] is True:
                        if x in layers:
                            op = myobj.MeasureGenerator[0]
                            #draw_segments(context, myobj, op, region, rv3d)
                            break

print()
print("test1:", timeit.timeit("test1()", setup="from __main__ import test1"))
print("test2:", timeit.timeit("test2()", setup="from __main__ import test2"))