Are you just getting disk spikes? Or does the disk cache meter creep up/remain overloaded? Does it affect playback, or is it just something you observed on the performance meter (F12)?
I ask this because Cubase’s transport controls causes disk cache spikes and I don’t think there’s anything you can do about it.
If you have an (otherwise empty) project with just 1 audio track without even audiofiles loaded/recorded, the disk cache meter will briefly overload (and just as quickly disappear) when you press Play/Stop/ and all the other transport controls.