I'm using exactly the same hardware I was using in V3, and it hardly registered on that version. I have projects with multiple instances o CS-80 V3, and never even considered the CPU usage as it was so low. Now, just one instance, and when I record enable that instance, the meters are close to hitting the limits.
Anyway. Windows. 64GB RAM. i7 8700K clocked with all cores at 5GHz. All SSD/NVMe drives.
I accept that demands may increase with time, but this is a quantum leap in CPU requirement.
I mean, I have projects with multiple CS-80 V3's and 70+ tracks with multiple VSTi's and VSTFX and the system isn't even struggling.
Then I have one test project with just one track with one CS-80 V4 and the CPU usage is becoming a problem.