diff --git a/crates/engine/src/settings/prefs/sections.rs b/crates/engine/src/settings/prefs/sections.rs
index ee86ce4c4..ca0e72bef 100644
--- a/crates/engine/src/settings/prefs/sections.rs
+++ b/crates/engine/src/settings/prefs/sections.rs
@@ -93,8 +93,11 @@ page!(Previews {
     /// Largest downsampling while playing back: `1/2`, `1/4`, `1/8`.
     adaptive_resolution_limit: String = "1/8".into(),
     /// A preview at Resolution Auto that renders slower than real time steps down a resolution
-    /// (½, then ¼, no further than the Adaptive Resolution Limit) for the rest of that play.
-    adaptive_playback: bool = true,
+    /// (½, then ¼, no further than the Adaptive Resolution Limit) for the rest of that play. Off
+    /// by default: it never steps back up during a play, so a looping preview kept playing at ¼
+    /// after its first loop, where without it the first loop caches Full and the next ones play
+    /// in real time at Full, as in After Effects.
+    adaptive_playback: bool = false,
     show_internal_wireframes: bool = false,
     cache_frames_when_idle: bool = true,
     fast_previews: bool = false,
diff --git a/crates/ui-egui/tests/it/ui_preview_align.rs b/crates/ui-egui/tests/it/ui_preview_align.rs
index 6b5525e09..9d3119b21 100644
--- a/crates/ui-egui/tests/it/ui_preview_align.rs
+++ b/crates/ui-egui/tests/it/ui_preview_align.rs
@@ -322,7 +322,7 @@ fn cache_frames_when_idle_survives_an_inverted_work_area() {
 
 /// Settings ▸ Previews ▸ Lower Resolution When Playback Can't Keep Up: a preview at Auto that
 /// stalls for two seconds steps down to half its scale, two more to a quarter; an explicit Resolution and
-/// the pref turned off keep the scale, and stopping goes back to the viewer's.
+/// the pref turned off (its default) keep the scale, and stopping goes back to the viewer's.
 #[test]
 fn playback_that_cannot_keep_up_steps_down_a_resolution() {
     let stall = |h: &mut Harness<'_, EffectcraftApp>, secs: f64| {
@@ -338,6 +338,8 @@ fn playback_that_cannot_keep_up_steps_down_a_resolution() {
         assert!(h.state().playback.playing);
     };
     let mut h = harness();
+    assert!(!h.state().session.prefs.previews.adaptive_playback, "off by default");
+    h.state_mut().session.prefs.previews.adaptive_playback = true;
     // No room in the RAM preview: frames never stay cached and every pass stalls, as with a comp
     // too heavy to render in real time.
     h.state().frames.set_budget(0);
diff --git a/docs/preferences.md b/docs/preferences.md
index cad74aec2..07df169aa 100644
--- a/docs/preferences.md
+++ b/docs/preferences.md
@@ -53,7 +53,9 @@ Commands (CLI, MCP, control channel):
 - `composition.showRenderingProgress`: Show Rendering Progress in Info Panel and Flowchart
 - `previews.adaptiveResolutionLimit`: Adaptive Resolution Limit (the lowest resolution Fast Previews ▸
   Adaptive Resolution drops to while you drag, and the lowest a playing preview steps down to)
-- `previews.adaptivePlayback`: Lower Resolution When Playback Can't Keep Up. On by default. A
+- `previews.adaptivePlayback`: Lower Resolution When Playback Can't Keep Up. Off by default (without it a first play renders
+  at the viewer's resolution at the rate frames arrive, and a looping preview plays its later loops
+  from the cache in real time, as in After Effects; with it the play stays lowered). A
   preview at Resolution Auto that plays under 80 % of its frame rate (frames render slower than
   that, so it plays them at the rate they arrive rather than freezing between them) steps
   down a resolution (half the scale after two seconds, a quarter two seconds later if still slow,