This post comes to you from Ubuntu 8.10 Intrepid Ibex, upon a fully encrpted 500GB disk. So if my laptop should fall into the wrong hands, my customers, family and friends can rest assured their data, passwords, photographs or emails are (for all practical purposes) secure.
Thus far I haven’t noticed a performance cost. The system “feels” as fast as before. I’m running a Centrino Core2 Duo 1.66GHz, 1.5GiB RAM. When moving large quantities of data (10GiB plus) I see the kcryptd process using around 25% – 50% CPU (of one core).