Unclear what "virtual slides" does

[MagnusBrzenk]

I am reading your documentation here: https://swiperjs.com/react#virtual-slides, and it's not clear what adding this 'virtual' stuff does. I'm guessing it's to do with rendering off screen, but not clear. I tried your demo with 500 slides, and the performance looks the same when I remove the virtual properties. Please clarify in documentation what is different when applying 'virtual' option.

[innocentdavid]

They should at least add preview to the examples in the doc