I've got about 70k image attachments. I bet just about none of them are optimized. This wastes a ton of disk space and bandwidth. It would be awesome if during the upload process the image could also be optimized/compressed. A tool to do this retroactively would also be appreciated
Read @Walter's attachment write up here. Specifically the problem/solution part. It basically makes XF resize almost every photo uploaded. While the resized is not perfectly optimized, it's a lot better than the huge size they are coming straight from the uploader.