I see most in this thread are pc based machines. I’ve been on a macbookpro for quite a while and had ALL the same issues I’ve read in this tread and others regarding the spikes. Cubase was unusable to me almost the entire month of January and into Feb. I was getting ready to (gulp) switch to Logic after fifteen years on Cubase it was so bad.
The reason I bring this up is because I finally updated my OS to Yosemite although Steinberg warned against it at the time. to be honest, it couldn’t have gotten worse. I also had cpu system freezing spikes with just a few vsts loaded on a new and empty project. Yosemite cleared up almost everything! I’ve been 80% happy with my setup. I still have more stuttering than the past but “render in place” saves me hours and HOURS of rendering large pop and orchestral projects that I was “hanging on” to the idea of making version 8 work. It’s been working for the past three months consistently.
I bring this up because my 2012 Mac has a NVIDIA GeForce GT 650M stock in it and it was the OS that changed everything on my end. I know several guys have had supposed NVIDIA issues.
Not sure how this may help a non mac user but it’s info to throw into the discussion.