and with the release of Lion with its AES based full disk encryption called File Vault 2 (FV2), I've been curious about performance hit from FV2.
As far as I can tell, using FV2 gives a file system performance hit of less than about 10%. So if you were to move to SSD from spinners and then use FDE / FV2 on Lion then you would still see a big gain in disk I/O.
Anyway, you can run some openssl benchmarks.
On my personal MBP a 2.53 core 2 duo
$openssl speed aes-256-cbc
Doing aes-256 cbc for 3s on 16 size blocks: 18280734 aes-256 cbc's in 2.96s
Doing aes-256 cbc for 3s on 64 size blocks: 4660089 aes-256 cbc's in 2.94s
Doing aes-256 cbc for 3s on 256 size blocks: 1196116 aes-256 cbc's in 2.98s
Doing aes-256 cbc for 3s on 1024 size blocks: 298821 aes-256 cbc's in 2.97s
Doing aes-256 cbc for 3s on 8192 size blocks: 36577 aes-256 cbc's in 2.92s
OpenSSL 0.9.8r 8 Feb 2011
built on: Apr 22 2011
options:bn(64,64) md2(int) rc4(ptr,char) des(idx,cisc,16,int) aes(partial) blowfish(ptr2)
compiler: -arch x86_64 -fmessage-length=0 -pipe -Wno-trigraphs -fpascal-strings -fasm-blocks -O3 -D_REENTRANT -DDSO_DLFCN -DHAVE_DLFCN_H -DL_ENDIAN -DMD32_REG_T=int -DOPENSSL_NO_IDEA -DOPENSSL_PIC -DOPENSSL_THREADS -DZLIB -mmacosx-version-min=10.6
available timing options: TIMEB USE_TOD HZ=100 [sysconf value]
timing function used: getrusage
The 'numbers' are in 1000s of bytes per second processed.
type 16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
aes-256 cbc 98934.37k 101410.31k 102676.20k 102983.81k 102790.17k
If you have AES-NI and your openssl has AES-NI ability you can run
$openssl speed –engine aesni –evp aes-256-cbc
If I find myself in an Apple store I might try running this.