diff --git a/frontend/js/videos.js b/frontend/js/videos.js
index b2c531e..8bf26c9 100644
--- a/frontend/js/videos.js
+++ b/frontend/js/videos.js
@@ -1331,15 +1331,60 @@ App.videos = App.videos || {};
         let builtCards = 0;
         let recycledCards = 0;
 
+        // ---------------------------------------------------------------
+        // Flinging
+        //
+        // A card that flies past costs far more than it costs to build. Its
+        // thumbnail is a request, a decode and a height correction; its title
+        // is a forced layout; its formats are a yt-dlp extraction on the
+        // server. Every one of those is work for a video the reader has not
+        // looked at, and during a fast scroll there are dozens of them.
+        //
+        // So a mount while flinging only *places* the card -- it takes its
+        // space in the layout, at the right size, with its text. Everything
+        // that costs is deferred to the moment the scroll settles, and only
+        // for the cards still on screen by then. Anything scrolled past in the
+        // meantime is unmounted having cost almost nothing.
+        // ---------------------------------------------------------------
+        const FLING_PX_PER_MS = 1.6;   // ~1600px/s, well past a deliberate scroll
+        const SETTLE_MS = 140;
+        let flinging = false;
+        let lastScrollY = 0;
+        let lastScrollAt = 0;
+        let settleTimer = null;
+        const unfilled = new Set();    // mounted indices still waiting to be filled
+
+        const noteScroll = function() {
+            const now = performance.now();
+            const y = window.scrollY;
+            const dt = now - lastScrollAt;
+            if (dt > 0 && lastScrollAt) {
+                flinging = (Math.abs(y - lastScrollY) / dt) > FLING_PX_PER_MS;
+            }
+            lastScrollY = y;
+            lastScrollAt = now;
+            if (settleTimer) clearTimeout(settleTimer);
+            settleTimer = setTimeout(settle, SETTLE_MS);
+        };
+
+        const settle = function() {
+            settleTimer = null;
+            flinging = false;
+            unfilled.forEach((i) => {
+                const card = mounted.get(i);
+                if (card) fill(i, card, state.loadedVideos[i]);
+            });
+            unfilled.clear();
+        };
+
         const acquire = function(v) {
             const card = pool.pop();
             if (!card) {
                 builtCards++;
-                return App.videos.buildCard(v);
+                return App.videos.buildCard(v, { skipThumbnail: true });
             }
             recycledCards++;
             App.videos.bindCard(card, v);
-            App.videos.attachThumbnail(cardRefs(card).img, v.thumb);
             return card;
         };
 
@@ -1380,9 +1425,19 @@ App.videos = App.videos || {};
             }
             grid().appendChild(card);
             mounted.set(i, card);
+            if (flinging) unfilled.add(i);
+            else fill(i, card, v);
+        };
+
+        // The part of a mount that costs: the thumbnail, the title measurement
+        // and the format resolve the observer triggers.
+        const fill = function(i, card, v) {
+            if (!card || !v) return;
+            unfilled.delete(i);
+            const img = cardRefs(card).img;
+            App.videos.attachThumbnail(img, v.thumb);
             // Once the thumbnail loads, drop the 16:9 placeholder so it shows at
             // its true aspect ratio, clear the shimmer, then correct the height.
-            const img = card.querySelector('img');
             if (img) {
                 const reveal = () => {
                     // Release nulls this, so a reveal already queued for a frame
@@ -1416,6 +1471,7 @@ App.videos = App.videos || {};
             const card = mounted.get(i);
             if (!card) return;
             mounted.delete(i);
+            unfilled.delete(i);
             release(card);
         };
 
@@ -1485,6 +1541,11 @@ App.videos = App.videos || {};
             return tailTop !== Infinity && viewTop + vh >= tailTop;
         };
 
+        const onScroll = function() {
+            noteScroll();
+            scheduleUpdate();
+        };
+
         const scheduleUpdate = function() {
             if (rafPending) return;
             rafPending = true;
@@ -1601,7 +1662,7 @@ App.videos = App.videos || {};
             if (initialized) return;
             initialized = true;
             settleWidth = window.innerWidth || 0;
-            window.addEventListener('scroll', scheduleUpdate, { passive: true });
+            window.addEventListener('scroll', onScroll, { passive: true });
             // orientationchange fires first (before the viewport metrics change),
             // which is exactly when the pre-rotation anchor is still valid.
             window.addEventListener('orientationchange', beginSettle);
@@ -1620,6 +1681,8 @@ App.videos = App.videos || {};
             // its own cards, and these are exactly the right shape for it.
             mounted.forEach((card, i) => unmount(i));
             mounted.clear();
+            unfilled.clear();
+            flinging = false;
             revealed.clear();           // new result set should animate in again
             layout.length = 0;
             colBottoms = [];
@@ -1641,7 +1704,8 @@ App.videos = App.videos || {};
         };
 
         const stats = function() {
-            return { built: builtCards, recycled: recycledCards, pooled: pool.length };
+            return { built: builtCards, recycled: recycledCards, pooled: pool.length,
+                     unfilled: unfilled.size, flinging: flinging };
         };
 
         return { ensureInit, packFrom, update: scheduleUpdate, relayout, removeVideo, reset, isNearEnd, stats };
diff --git a/tests/smoke_grid.py b/tests/smoke_grid.py
index 6d62a48..fbf76c8 100644
--- a/tests/smoke_grid.py
+++ b/tests/smoke_grid.py
@@ -170,7 +170,16 @@ def check_cards(c, cards, phase):
 def main():
     c = Checks()
     with sync_playwright() as p:
-        browser = p.chromium.launch(args=["--no-sandbox"])
+        # Lean launch flags: this runs alongside the app's own server, and a
+        # default Chromium spikes hard enough at startup to get itself killed on
+        # a constrained box.
+        browser = p.chromium.launch(args=[
+            "--no-sandbox",
+            "--disable-dev-shm-usage",
+            "--disable-gpu",
+            "--renderer-process-limit=1",
+            "--js-flags=--max-old-space-size=512",
+        ])
         page = browser.new_page(viewport={"width": 1400, "height": 1000})
         boot(page)