A few weeks ago, I got my new MBA, 11", 2GB Ram, 64 GB Toshiba SSD. I've just measued the difference in SSD speed between the unencrypted and the encrypted system. Due to the encryption, my SSD gets about 20% slower. (180 MB/s vs. 220 MB/s) Since the new Intel Core I processors support the AES-NI, the CPU usage during encryption is negligible. (The Truecrypt benchmark shows over 800 MB/s of AES in Ram) This means: All the benefits of encryption come pretty much for free. Now just imagine you loose your MBA or it gets stolen. The thief can read all of your emails, look at all your pictures on your MBA. He can also put your emails and pictures onto the web together with you full name. Maybe he can also log into your facebook-account and write messages to your friends under your name. Does this sound like something you would like? So my question is: Why is not everyone using encryption? What reasons do you have to keep it turned off?