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I'm thinking of using FileVault to secure my computer - it looks like an ideal solution for everything. However, I'm wondering - will it effect the performance / battery life of my computer significantly?

I've got a 2010 MBP with 8gb RAM and a 500gb WD HDD, and the battery at the moment is good for about six hours. I'm running OSX10.7.1.

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I can't comment on how Lion's FileVault 2 affects battery life, but I've had it running (Full Disk Encryption) on an older (2007) MacMini with 3GB of RAM for a few months, and it is a great solution for keeping a computer that might get stolen secure.

Beyond the initial encryption, which took a few hours, I really haven't noticed any performance difference. Given that this is an older machine, any negligible difference I might have missed would be even smaller on a newer machine like yours.

I was curious about this myself at the time and found this AnandTech article, which boils it down to a negligible CPU load, and a slight hit to your hard drive's throughput. They were using an SDD though, so the results may not exactly correspond with a spinning disk.

So if you're reading and writing to the disk a lot, you might notice a slight decrease in battery life as reads and writes will take a bit longer, but I doubt it'd be anything too drastic.

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I asked a Genius in the Apple store while I was there and he pretty much backed up what you said, but mentioned that the increased I/O has a detrimental effect on Battery life. He recommended 'Protect Files' (apimac.com) as I'm only looking to protect a single software project I'm working on. Is there an alternative to full disk encryption with FileVault? I've never gone past the recovery key stage so don't know how many options there are. – George Pearce Dec 31 '11 at 18:54
If it's just a specific set of files that you're trying to protect, why not use something like Truecrypt? You create an encrypted virtual volume (basically a big blob of pre-allocated space that exists as a file on your Mac's drive). Then you put your files into the encrypted volume. You'll be required to put in your password each time you mount the volume to access the files. Even though I use FileVault, I still use Truecrypt to protect certain things, like backed up lists from password management software. – Vickash Dec 31 '11 at 21:12
Protect Files looks like it does something similar to Truecrypt in a much more user friendly way. Truecrypt is a bit more difficult to use, but it's free and allows a lot of customization of what filesystem the virtual disk uses and what types and strengths of encryption to use. – Vickash Dec 31 '11 at 21:17
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This depends on whether your MBP has an Intel processor which supports Intel® Advanced Encryption Standard (AES) which is also used in Filevault 2.

Ars Technica, published an extended review on Filvault 2 in Lion. They say:

Apple also leverages the special-purpose AES instructions and hardware on Intel's newest CPUs, further reducing the CPU overhead. The end result is that regular users will be hard-pressed to notice any reduction in performance with encryption enabled.

My experience

Hardware: Intel 2635QM (MBP early 2011) which supports AES encryption and Crucial M4 128GB SSD.

I'm downloading, listening to music, have several applications running, and SophosAV live scan enabled. My processor stats using iStat Pro: Idle 97%

  • I have noticed a drop in read speeds of merely 4%.
  • As the overall CPU load is nearly unchanged, the battery life is not affected significantly: In overall power consumption I will neglect the power drain of the SSD. The CPU and hard drive are the only significant factors that change the power consumption when disk encryption is enabled, I assume.

In answer to your question

See this list which compares all Intel processors used in the MBP released in 2010 (scroll to bottom, look for 'AES New Instructions'). Only four out of the six processors support AES instructions. However, it is possible that Apple did not choose to enable this functionality. This happened to my 2635QM. AES support was added later via a firmware update.

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