This will depend on which model 15 is purchased a Dual Core i5 or a Quad Core i7
For the record I would not purchase anything with just 2 Cores in this day and age. Nor would I would I Purchased a 6th Generation Core i7 if you care about heat and performance.
And that AMD Radeon 450 GPU yuck.
I'm gonna patiently wait for Kaby Lake and decent NVIDIA GPU. And Apple product with AMD inside simply does not earn my money.
It's like buying BMW M5 factory junk when for the same money you can buy a hand built Mercedes AMG product. Night and day.