> ... That being: "Can I decode the next frame(s) in time to show it/them without stuttering".

Except when you are editing video, or rendering output. When you have multiple streams of very high definition input, you definitely need much more than realtime speed decoding of a single video.

And you would want to scrub around the video(s), jumping to any timecode, and get the target frame preferably showing as soon as your monitor refreshes.