I really thought/hoped that Steinberg was able to optimize the
CPU usage and thread usage (optimization) in version 9, really really hoped it would be so much better than 8.5 but unfortunately not.
In my case, Cubase use about 24/25 percent of my CPU power? 
Please let the developer know, so maybe this happens in ver 9.5? 
Regards
Mikael
Intel i74930 (6 cores and 12 threads)
Ram: 32GB
SSD 500GB x 3
Windows 10
RME AIO Sound card