Wouldn't Cloudflare free plan with sub domain for the static be all you need - plus you get the kickass DNS for your domain?
https://www.cloudflare.com/plans/
First - don't have folder with 1 mil image files. :-)
- Can you turn off the directory file listing with the FTP client? This might stop it from choking.
- Or you could remove the image via SSH. Adding could be done with rsync over ssh.
- Or have a PHP file to upload the images and move the...