WP Smush Pro
Smush Pro now lets you smush images up to 32MB. That’s more than enough for most people’s needs.
The backend of the plugin includes options to auto-smush on upload (so you don’t have to individually smush images) and “super smush” for lossy optimization. This last option promises two times more compression than lossless, with almost no noticeable quality loss. You can also choose to backup original images, though this will nearly double the size of your uploads directory.
Smush Pro uses WPMU DEV servers to smush your images, so you don’t have to worry about additional load on your servers.