Install the latest version from https://github.com/scikit-image/scikit-image. Just a few days ago I fixed a bug (see https://github.com/scikit-image/scikit-image/commit/d5776656a8217e58cb28d5760439a54e96d15316) related to this slow down.
My numbers are as follows with the current dev version:
from PIL import Image
import numpy as np
from skimage.transform import rotate
a = np.zeros((1000, 1000), dtype=np.uint8)
im = Image.fromarray(a)
%timeit im.rotate(10, Image.BICUBIC, expand=True)
ima = a / 255.0
%timeit rotate(ima, 10, order=1)
%timeit rotate(ima, 10, order=3)
## -- Output --
10 loops, best of 3: 41.3 ms per loop
10 loops, best of 3: 43.6 ms per loop
10 loops, best of 3: 101 ms per loop