We keep working on actual benchmarking but it's somewhat tricky to get reliable numbers... We're working on it now. Sometimes it's 'favorable' sometimes it's not. That's kind of a non-committal answer from me, but that's the best I've got for you at this time.
I'd expect wireguard to often be faster due to its protocol/implementation. I've seen people complain about wireguard if you don't set the MTU. Maybe you'll try them both out and blog about it??? :) (that'd be pretty cool regardless of the outcome tbh).
What I usually tell people, is that I use OpenZiti/zrok all the time. As a human, I don't even notice it. Sorry we don't have better details at this time but hopefully that a reasonable answer