Performance - low buffer

Dear Forum,

I am sure this question is pretty basic. I am experienced on some DAWS and they all handle this topic a bit different.

If you´d be so kind to give a short info on that in Cubase 10.5

I tend to render the MIDI Instruments at a pretty early stage to save on CPU load. I would like to keep the live playing chance to a pretty final stage in bigger projects setting the buffer at least to 128 samples on my desktop WIN 10 machine.

So:
How to make sure that the rendered audio tracks are played and the original MIDI Instrument tracks don´t consume any CPU load (are turned off completely not only muted)?

THX
BX

Just disable the MIDI instrument or track