Alright, here are some numbers on my R7 1700. Source was a 1080p BD I had handy. Options were:
-q 30 -n 1000 -i stdin -w 1920 -h 1080 -enc-mode 4
Code:
Total Frames Frame Rate Byte Count Bitrate
1000 30.00 fps 5734937 1376.38 kbps
Channel 1
Average Speed: 1.853 fps
Total Encoding Time: 539574 ms
Total Execution Time: 541517 ms
Average Latency: 47668 ms
Max Latency: 64363 ms
Encoder finished