FileVault performance on Mac Pro 5,1

[Taipan]

Hi!

I'm still using a trusty old Mac Pro 4,1 (8x 2,93 GHz) flashed to 5,1 with Mojave. I have just bought a new 2TB SSD, and I'm thinking about enabling FileVault. But I'm wondering about a performance hit, since I suppose these CPUs don't support AES encryption natively.
Also, I read about Mac Pro 5,1 not being compatible wih FileVault under Mojave, but that might have just been referring to the upgrade process from an older system as such.

Can someone give me an info on that? Searching revealed little info specifically for older devices.
Thank you!

 

[Taipan]

OK, I guess the question is moot. Apparently it's true that FileVault is not available on the older Mac Pros under Mojave. Apple's reasoning is that one could be using graphics cards without Mac EFI that wouldn't be able to display the password screen pre-boot.
In my opinion it can't be that hard to check whether the card can do it or not, but that's Apple.