I'm curious to know as I have a Mac and I want to play Rainbow Six Siege via VirtualBox but I don't want it to be a waste if it lags too much.
You'd be better off putting windows on your mac alongside than to game with virtual box. So yes, heavy games like Rain Six Siege will not work or be extremely laggy.
I use bootcamp on my MacBook to play r6 but i’ve used an vm before. Playing games on vm is a complete pain to begin with, not just that downloading the game also requires a lot more patience (since your bandwidth is shared with Mac OS also). Overall don’t use vm.
Meanwhile on boot camp you’ll find the best performance you can ever get on an MacBook.
In r6 siege I got 30 FPS max on the lowest setting, 1028x920. But you’ll have to turn on v sync or else you’ll be impossible to see because of the screen tearing.
Specs: mb pro late 2013 13in, i5 4258u iris gpu, 8gb ram