diff --git a/src/renderer-vod-hover.ts b/src/renderer-vod-hover.ts
index a57793b..f754d6e 100644
--- a/src/renderer-vod-hover.ts
+++ b/src/renderer-vod-hover.ts
@@ -21,6 +21,20 @@ let pendingHoverVodId: string | null = null;
 const HOVER_DEBOUNCE_MS = 220;
 const FRAME_INTERVAL_MS = 600;
 const FRAMES_TO_CYCLE = 4;
+// Bounded cache — each storyboard data URL is ~50-200 KB, so an
+// unbounded cache could balloon to hundreds of MB on a long browsing
+// session through a streamer with thousands of VODs. FIFO eviction
+// keeps the working set fresh without manual cleanup.
+const MAX_CLIENT_STORYBOARD_CACHE = 100;
+
+function rememberStoryboard(vodId: string, sb: VodStoryboard | null): void {
+    vodStoryboardClientCache.set(vodId, sb);
+    if (vodStoryboardClientCache.size > MAX_CLIENT_STORYBOARD_CACHE) {
+        // Map iterator is insertion-ordered — first key is the oldest.
+        const oldestKey = vodStoryboardClientCache.keys().next().value as string | undefined;
+        if (oldestKey !== undefined) vodStoryboardClientCache.delete(oldestKey);
+    }
+}
 
 function ensureVodHoverHandlersBound(): void {
     const grid = document.getElementById('vodGrid');
@@ -85,7 +99,7 @@ async function activateHoverPreview(card: HTMLElement, vodId: string): Promise<v
         } catch (_) {
             storyboard = null;
         }
-        vodStoryboardClientCache.set(vodId, storyboard);
+        rememberStoryboard(vodId, storyboard);
     }
 
     // Cursor may have moved on while we awaited; re-check guard.