What does VIC-II do when switched "off"?

I've been studying the things the VIC-II does when sharing the data bus with
the CPU. I'm talking about fetching data for text, graphics, color and
sprites. And then, refreshing the DRAM.

But... what if I turn the VIC-II "off"? What does it do when I want no
graphics at all? Just refreshing DRAM? does it stop accessing the bus and
reading all the memory locations it needs or does it just do it every time,
no matter if it's displaying something?

I'm asking this, because I'm having the idea of this GPU cartridge for the
Commodore 64, where the VIC-II is not used at all, so the CPU has all the
cycles it can use during its turn of the clock cycle available for it, with
no badlines or color ram or sprites interfering that make the VIC-II stop
it.

Thanks for answers.



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