here's the bench test results recorded last year on sonar x1 using windows 8:
http://blog.cakewalk.com/windows-8-a-benchmark-for-music-production-applications/#more-8777 and here is a little piece of that article,
SONAR CPU load at low latency
SONAR CPU gains were observed when using Windows 8 for Low latency performance tests. These gains mean you can run bigger loads in Win8 at low latency without audio glitching.
low latency plugins… 15.5% CPU reduction
input monitoring… 8% CPU reduction
high track count… 23% CPU reduction
High bandwidth audio …6.2% CPU reduction
SONAR multi-core CPU load balancing at low latency
Workloads for cores are more evenly balanced at low latencies on Windows 8. Better balanced core workloads translate to more efficient use of multiple CPU core hardware and thereby better workload scaling for large projects.
low latency plugins… 23% improvement
input monitoring… 31.7% improvement
high track count… 30.6% improvement
High bandwidth audio …17.5% improvement
Memory usage
A 7.9% reduction in memory use under Win8 was observed when loading a large real world SONAR project (Cori Yarkin project from SONAR sample content) under identical system configuration. Reduced memory load can be observed in most of the tests.
Disk Performance
A 78% improvement under Win8 was observed in disk read/write performance while reading large buffer sizes. Improvements were more moderate at smaller buffer sizes.
System calls per second
An 85% reduction in system calls was observed under Windows 8 in the input monitoring case and more moderate gains in the other cases. Fewer system calls translate to improved CPU load as well as fewer user mode to kernel transitions which mean fewer audio glitches.
Kernel use
25 – 50% reduction in kernel use can be observed in some of the tests with Win8. Lower kernel use results in fewer audio glitches since it leaves more headroom for audio drivers.
Conclusion
All the tests above were done running the current shipping version of SONAR X1 with no special Win8 tweaks. The tests ran very smoothly with no problems noted under Win8 using SONAR X1. In fact you could push the system harder under Win8 without getting glitches in audio as compared to Win7. The tests show that despite the controversial changes to Windows, there are some significant benefits even for standard Windows desktop apps running Windows 8. This is great news for existing Windows 7 users who are considering an upgrade to Windows 8.
now this isn't like a pretty decent improvement, this is huge.