Moving from 6.1 to 8.x: Hardware Performance and Requirements

Hello!

We're evaluating a move from 6.1 to 8 (first to 8.0, then to
8.03.400). Can anyone out there give me an idea of how much better or
worse version 8.x performs compared to 6.1?

Should we expect to have to upgrade our servers in order get the same
level of performance we now have with 6, or will it perform even better
on the same hardware?

Thanks for your help!