I have wondered if the encoders used by tools like ffpmeg and hardware encoders like NVENC are more efficient for common resolutions like 1920x1080. I've done a few informal tests with a variety of resolutions and I haven't seen 1080p to be any faster than any other nearby resolution. The documentation for NVENC gives max resolutions supported, but no indication that any are specialized. AVC has different levels specifying maximum frame size and bitrate, but again nothing indicates one resolution optimized for specifically.