If you ever wondered what tool to use for backing up your data, search no more. Frost does what you want, it's fast, does not consume too much CPU, does not consume too much memory, does not consume too much disk space. It's safe, it's easy to use.
Frost makes use of deduplication.
This means it'll never consume twice your file size if you add a single line somewhere in your file and re-backup.
Since v2.0, Frost uses its own index format that's a lot faster than database based solution (like SQLite3).
This means that backing up and restoring a huge collection is darn fast. It's fast enough that you can use FUSE to browse your backup like if it was local to your machine (no, I did not say Time Machine... cough).
Frost encrypts your data.
You can save your backup set on an untrusted server and it's safe. Frost uses high strength AES256 encryption that's well documented so you can not disclose your data by error.
Frost provides a FUSE client.
This means you can mount your backup set like a local drive, see each backup as a single unique version of your files, and, thanks to deduplication, without using too much disk space.
A detailled usage guide is available here.
The source code is here.