diff --git a/docshell/base/BrowsingContext.cpp b/docshell/base/BrowsingContext.cpp
index 405ad6a0bef0..54bb69fc066d 100644
--- a/docshell/base/BrowsingContext.cpp
+++ b/docshell/base/BrowsingContext.cpp
@@ -2750,6 +2750,9 @@ void BrowsingContext::DidSet(FieldIndex<IDX_ExplicitActive>,
 
   PreOrderWalk([&](BrowsingContext* aContext) {
     if (nsCOMPtr<nsIDocShell> ds = aContext->GetDocShell()) {
+      if (auto* bc = BrowserChild::GetFrom(ds)) {
+        bc->UpdateVisibility();
+      }
       nsDocShell::Cast(ds)->ActivenessMaybeChanged();
     }
   });
diff --git a/dom/base/Document.cpp b/dom/base/Document.cpp
index f569af64324e..168d0b63f24f 100644
--- a/dom/base/Document.cpp
+++ b/dom/base/Document.cpp
@@ -16857,7 +16857,6 @@ void Document::UpdateIntersections(TimeStamp aNowTime) {
 
 static void UpdateEffectsOnBrowsingContext(BrowsingContext* aBc,
                                            const IntersectionInput& aInput,
-                                           bool aIsHidden,
                                            bool aIncludeInactive) {
   Element* el = aBc->GetEmbedderElement();
   if (!el) {
@@ -16870,8 +16869,14 @@ static void UpdateEffectsOnBrowsingContext(BrowsingContext* aBc,
   const bool isInactiveTop = aBc->IsTop() && !aBc->IsActive();
   nsSubDocumentFrame* subDocFrame = do_QueryFrame(el->GetPrimaryFrame());
   rb->UpdateEffects([&] {
-    if (aIsHidden || isInactiveTop) {
-      // Fully hidden if in the background.
+    if (isInactiveTop) {
+      // We don't use the visible rect of top browsers, so if they're inactive
+      // don't waste time computing it. Note that for OOP iframes, it might seem
+      // a bit wasteful to bother computing this in background tabs, but:
+      //  * We need it so that child frames know if they're visible or not, in
+      //    case they're preserving layers for example.
+      //  * If we're hidden, our refresh driver is throttled and we don't run
+      //    this code very often anyways.
       return EffectsInfo::FullyHidden();
     }
     const IntersectionOutput output = DOMIntersectionObserver::Intersect(
@@ -16921,17 +16926,16 @@ void Document::UpdateRemoteFrameEffects(bool aIncludeInactive) {
   auto margin = DOMIntersectionObserver::LazyLoadingRootMargin();
   const IntersectionInput input = DOMIntersectionObserver::ComputeInput(
       *this, /* aRoot = */ nullptr, &margin);
-  const bool hidden = Hidden();
   if (auto* wc = GetWindowContext()) {
     for (const RefPtr<BrowsingContext>& child : wc->Children()) {
-      UpdateEffectsOnBrowsingContext(child, input, hidden, aIncludeInactive);
+      UpdateEffectsOnBrowsingContext(child, input, aIncludeInactive);
     }
   }
   if (XRE_IsParentProcess()) {
     if (auto* bc = GetBrowsingContext(); bc && bc->IsTop()) {
       bc->Canonical()->CallOnAllTopDescendants(
           [&](CanonicalBrowsingContext* aDescendant) {
-            UpdateEffectsOnBrowsingContext(aDescendant, input, hidden,
+            UpdateEffectsOnBrowsingContext(aDescendant, input,
                                            aIncludeInactive);
             return CallState::Continue;
           },
diff --git a/dom/ipc/BrowserChild.cpp b/dom/ipc/BrowserChild.cpp
index 2d3a47d46e7c..163f4fc4b29b 100644
--- a/dom/ipc/BrowserChild.cpp
+++ b/dom/ipc/BrowserChild.cpp
@@ -3028,20 +3028,23 @@ void BrowserChild::UpdateVisibility() {
     if (mBrowsingContext && mBrowsingContext->IsUnderHiddenEmbedderElement()) {
       return false;
     }
-    // For OOP iframes, include viewport visibility. For top-level <browser>
-    // elements we don't use this, because the front-end relies on using
-    // `mRenderLayers` when invisible for tab warming purposes.
-    //
-    // An alternative, maybe more consistent approach would be to add an opt-in
-    // into this behavior for top-level tabs managed by the tab-switcher
-    // instead...
-    if (!mIsTopLevel && !mEffectsInfo.IsVisible()) {
-      return false;
-    }
     // If we're explicitly told not to render layers, we're also invisible.
     if (!mRenderLayers) {
       return false;
     }
+    if (!mIsTopLevel) {
+      // For OOP iframes, include viewport visibility.
+      if (!mEffectsInfo.IsVisible()) {
+        return false;
+      }
+      // Also include activeness, unless we're artificially preserving layers.
+      // An alternative to this would be to propagate mRenderLayers from the
+      // parent, perhaps, so that it applies to the whole tree...
+      if (!mIsPreservingLayers && mBrowsingContext &&
+          !mBrowsingContext->IsActive()) {
+        return false;
+      }
+    }
     return true;
   }();
 
@@ -3091,6 +3094,7 @@ void BrowserChild::MakeHidden() {
 IPCResult BrowserChild::RecvPreserveLayers(bool aPreserve) {
   mIsPreservingLayers = aPreserve;
 
+  UpdateVisibility();
   PresShellActivenessMaybeChanged();
 
   return IPC_OK();