I wasn't speaking of a 4k TV, but still, this doesn't check out. A single 2160p framebuffer is 8MPix, or 32MiB. Not counting the original FB size, the extra 1.5GiB are enough for 48 whole framebuffers. You don't need that much image data all at once, the number is ridiculous. No, I believe it's just that the code became that much less efficient.