Alternatively if you want speed and full Pillow compat, you can also easily replace Pillow by Pillow-SIMD.
Benchmarks: https://python-pillow.org/pillow-perf/ 37
And be careful on the algorithm you choose. For example there are clear tradeoff in image quality vs resizing speed for Lanczos vs bicubic vs bilinear interpolations/

http://tanbakuchi.com/posts/comparison-of-openv-interpolation-algorithms/ 14
http://pixinsight.com/doc/docs/InterpolationAlgorithms/InterpolationAlgorithms.html 8