I have both a Focusrite Scarlett 2i4 and an Apollo Firewire Quad 2. Both give similar results. On the Apollo I seem to be getting audio drop outs even when playing a simple project with no plugins which I guess is a problem with the Apollo itself because the Focusrite doesn’t do that.
I don’t use the grid editor in SD3. I use the Cubase drum editor.
I don’t have an onboard GPU.
I tried going back to Normal Audio Priority. Can’t say there was much of an improvement.
I opened the problematic project today again and unfroze everything. It actually ran fine for some time. Then I opened a plugin to try and do some mixing and it started popping and crackling. Closed the project and opened it again - Now it’s crackling even with everything frozen.
I will try the BitSum and audio tuning guide suggested my KHARMA probably tomorrow and will write back. In the meantime I’m still open to more suggestions