Well just use logic as it works better for you, simple.
If you want to use cubase change the way you work , simple
What are we on this self help user forum supposed to do for you
Personally I would try and find out whether your cubase performance is nomal compared with other users on your type of rig
100 blank Kontakt 5 instrument traks here measure less that 10 percent on the aiso meter here
Hippo