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After posting the previous article, I have done some tests on a disk encrypted with PGP WDE, and benchmarks show that the performance hit is quite big. Strangely, there is no visible difference during the normal use.

Test Conditions

The test has been run on two identical Macbook Pro C2D 2.4GHz machines, with Mac OS X10 .5.7. Both machines use the same internal hard disk: Western Digital Scorpio Black  320 GB 7.2k RPM (WD3200BEKT). One of the machines has the internal disk fully encrypted with WDE.

The test has been conducted using QuickBench by Intech Software; this application runs the same tests using blocks of different sizes, I am reporting the average over all block sizes.

Looking at the average over the difference tests, the performance hit of WDE is roughly 34%. As mentioned above, I am surprised by these figures: I have used WDE for some time, and there is no perceptible difference in performance.

Update (July 6, 2009)

You might want to look at this thread on the official PGP forums:

… I can only conclude that disk benchmarks are not a good performance measure, as they do not reflect typical disk usage.

Reply from PGP: Your conclusion is fundamentally correct. XBench is designed to test disk performance. As such it bypasses the internal file system level buffers that provide much of the performance improvements that you see when using your Macintosh. XBench is a good measure of raw disk performance, but not of typical file system usage.