Hi @1stoptravel
Let me put it this way: it shouldn’t interfere with it but I can’t tell you if them both working together will “add up” for “more optimization” significantly.
CloudFlare’s Polish works, pretty much like entire CloudFlare, “in between” your site and end user. So whatever it does to images, it does it to them after they are already fetched from your site.
If you optimize images with Smush, such already optimized images will “pass through” the CloudFlare. I suppose that for some of them Polish may add a bit more compression/optimization and for some there’ll be no further change.
It shouldn’t conflict, though.
What could, however, be beneficial in this situation would be that with Polish at least some of these images would be cached at CloudFlare (which means faster delivery to the end-user) and also whenever an image is not in CF cache and has to be fetched to it from your site – it also will be fetch faster as it will be a smaller file (because it’ll be already compressed by Smush).
So overall, there might be some slight additional benefits and it shouldn’t conflict.
Best regards,
Adam