Hello
I have no idea how this Vormetric CoreGuard works exactly, never seen the product.
nevertheless, when you have encryption... then it means it is slow.
You will need CPU and good disks. The quicker your disks are (stripping/ssd/...), the drop of performance shouldn't be an issue, it will still be there.
Then it depends also on what kind of encryption you are using, the quality of the encryption (128bits, 4096bits, ...) all of that will have an impact on performance.
You can also check how much memory your application are using for caching... the more the application can cache its data before writing/reading the better.
Doesn't help with the initial 2008 question, but maybe that could help a bit...
Sincerely yours,
Alessandro