I am setting up a laptop ( its a macbook air to be exact ) to use Linux exclusively. My questions is what from a performance and battery saving point of view would work best here for making sure the laptop is secure at rest using encryption. My biggest concern is the performance and CPU overhead that each type of scenario provides. I think LVM might be overkill on a single disk laptop that probably wont be changing partition sizes that much.

1. Create a Encrypted partition and then use LVM on top of that to create root and home.
2. Create 2 encrypted partitions and mount them as root and home.
3. Do something exotic like make an encrypted partition make it root and then mount home as a loop-back file that resides on the root partition.
4. do something else. ( suggestions )

Thanks for your suggestions

1 and 2 won't have much difference. If you have an intel cpu later than sandybridge then it would have aes-ni intructions. Hard disk transfer performance won't fall that much but cpu utilization would be higher if have higher disk I/O. But you will have to use a energy meter to measure reality.

i would just use full drive encryption
most if not all install dvd's will have that option

just use a VERY LONG pass phrase
like
"TakeYourStinkingpawsOffMeYouDamnDirtyApe "
but not that famous line
"it'sAMadHouse,AmadHouse... "