Although I'm a Cakewalk Sonar lover,
But. I don't like their new user interface at all.
I think CPA 9.0's interface is more convenient.
And I found Sonar's DX-i use more resource than VST.
I tested by using the same software synth, one is DX-i, another is opened by VST-DX adaptor. About 5~7% CPU meter more
But I think it's the Direct X 8.0's problem.
DirectX is not only for Audio, also for Video, game,......