What’s normal: Best quality on a long song is heavy. With a supported GPU it’s usually minutes; on CPU-only machines a full song can take a long time — the progress bar and ETA keep moving the whole way.
Two things that bite:
- System sleep. If your computer sleeps mid-render, the render stalls or looks impossibly slow afterwards. Set your machine not to sleep for long renders (ReStem keeps the machine awake during a render on current versions, but screensaver and lid-close policies vary).
- “It’s stuck at 99%.” The last phase (MIDI trigger detection) on very long files can take a few minutes with the bar sitting near the top — give it time before force-quitting, and update to the latest version, which keeps the progress display moving through this phase.