Standard user experience amounts to about a 2.5-5% performance degradation on a machine that is PGP WDE encrypted. If you manage the server, you can try AES 128-bit encryption instead of 256-bit which does add some additional performance benefit at the cost of crypto strength.
The major painpoint for customers today is modern hardware with large disks and resuming from Hibernation. you can see 2-3 times the bootup time when resuming from hibernation due to limitations with the PGP WDE mini kernel that we boot which is operating in a 16-bit mode. This is even more noticable on a modern system with quad-core and eight-core processors with 16 gig's of ram since they are used to the system booting very quickly and when it's running in this 16-bit mode it's much slower.
We did make some code improvements to the behavior with hibernation in regards to failure in resuming hibernation (specifically hybrid sleep mode) in 10.2.1 MP5 (generally available through FileConnect). But no performance improvements as of yet. I'm willing to bet, where end users complaining the most - it's due to this limitation with hibernation.
In summary:
- don't use hibernation (2 to 3x better bootup times)
- try using aes 128bit instead of 256 bit
Docs for reference:
Blog on AES-128bit vs AES-256 bit
http://lukenotricks.blogspot.com/2010/04/aes-128-versus-aes-256-encryption.html
HOW TO: Enable AES-128 for PGP WDE in a PGP Universal Server 2.12 Environment
http://www.symantec.com/docs/TECH149717
Feature Request: Hibernation significantly slower after installing PGP
http://www.symantec.com/docs/TECH184961