Running Cubase 5 in Parallel on Macbook Pro non-retina

Hi guys, after trying to use Cubase 5 in Parallel, I found out it is not a good place to get in, I need to set the buffer to at least to 4096 to get it smooth. By default it is 2048, and I got crackling sound when I play it, for mixing maybe it still workable, but for recording totally useless… So at the end I go for Bootcamp and to get rid of others portential problem in the future…

Note that I am using MacBook Pro 13 inch without retina and without any audio interface.