So I downloaded a file off youtube. I checked the codec in this 8k file, and the codec is
Codec: H264 - MPEG-4 AVC (part 10) (avc1)
So I'm trying really hard to either convert a file to this codec, or install this codec into premiere pro.
Sorry, you're looking at it from the wrong point of view.
I can render a 1080p and a 4k h.264 in the same amount of time, or similar amount of time, maybe 50% longer for the 4k version. However when I render the video in quicktime, mpeg4, the render time goes up ten fold for the 1080p video, 15 times for the 4k video. The quicktime mpeg4 codec is taking ten times longer than the h.264.
The computer details are pretty irrlevent, but if you are curious, it's pretty high end. I have a 4930k @ 4.8 ghz with 32 gb ram and a titan video card.