Is there a way to turn off the uninterrupted previews feature? I don't find this feature useful as it has added two more keystrokes to my workflow (for some reason pressing space bar once doesn't stop playback, I need to hit it twice).
That's the new behavior. Options are available in the preview panel as before. Once the preview has rendered the first time, for example setting the work area and set to preview the work area, a single click of the space bar will stop the preview. If the preview has not rendered completely then hitting the space bar the first time will loop the preview. Many like this behavior, some do not. It takes some getting used to. Escape will always stop a preview.