The pace counted cached frames among the next ahead x 2, but the prefetch never requests more than the RAM preview holds (offsets 0..fit-1 from the current frame). With room for only a few frames the lead could never fill, so a preview that rendered every frame at once was slowed to a fraction of its frame rate, with Lower Resolution When Playback Can't Keep Up off (the default). The lead is now counted over at most the frames the prefetch keeps after the current one, and with none of those (room for at most two frames) the clock runs in real time as before pacing.
FredApps
114fbaed63