diff --git a/src/components/VideoPlayer.vue b/src/components/VideoPlayer.vue
index d869e6d6..c4b4db7a 100644
--- a/src/components/VideoPlayer.vue
+++ b/src/components/VideoPlayer.vue
@@ -972,4 +972,16 @@ defineExpose({
         max-width: none !important;
     }
 }
+
+/* Suppress Firefox/Gecko's blue :focus outline on the <video> element.
+   We explicitly .focus() the video on seek-bar mouseup (so hotkeys-js keeps
+   receiving keys), and Gecko draws a system focus outline whenever a <video>
+   is focused. Chromium uses :focus-visible heuristics on media elements so it
+   doesn't render the outline for click-driven focus. Kept outside @layer so
+   it wins over any layered rule, and !important to override the UA focus ring
+   if specificity gets shadowed. */
+video.shaka-video:focus,
+video[data-shaka-player]:focus {
+    outline: none !important;
+}
 </style>
diff --git a/src/main.js b/src/main.js
index eb0c54aa..641eb778 100644
--- a/src/main.js
+++ b/src/main.js
@@ -1,3 +1,4 @@
+import "@/utils/firefoxMediaCapabilitiesFix.js";
 import { createApp } from "vue";
 import router from "@/router/router.js";
 import App from "./App.vue";
diff --git a/src/utils/firefoxMediaCapabilitiesFix.js b/src/utils/firefoxMediaCapabilitiesFix.js
new file mode 100644
index 00000000..ad4a7d5b
--- /dev/null
+++ b/src/utils/firefoxMediaCapabilitiesFix.js
@@ -0,0 +1,56 @@
+/**
+ * HACK: Firefox-only fast path for navigator.mediaCapabilities.decodingInfo().
+ *
+ * Rough comparison: Chromium ~0.1 ms/call vs Firefox ~20 ms/call.
+ * Shaka calls decodingInfo once per Variant while filtering the manifest, so on
+ * a YouTube-shape manifest with many Variants Firefox stalls several seconds at
+ * player init before any SourceBuffer is added.
+ *
+ * This module delegates "supported" to MediaSource.isTypeSupported (sub-ms on
+ * Firefox) and synthesizes smooth = powerEfficient = supported.
+ *
+ * KNOWN DOWNSIDE: by forcing smooth and powerEfficient to true we discard the
+ * native signals Shaka would otherwise see. If anything in the player chain
+ * reads those fields (e.g. preferredDecodingAttributes is set, a downstream
+ * consumer ranks variants on power efficiency, or a Shaka upgrade changes
+ * filtering), this shim will cause Shaka to pick streams the device cannot
+ * decode in real time — frame drops, software-decode CPU spikes, battery
+ * drain. Today (Shaka 5.1, Piped default config) those fields are not read
+ * and the shim is harmless; revisit on every Shaka upgrade.
+ *
+ * Active only on Gecko engines, so Chromium / Safari / Edge / iOS Firefox
+ * (WebKit) are unaffected. DRM probes (keySystemConfiguration) and non-
+ * media-source query types fall through to the native API unchanged.
+ *
+ * Refs:
+ *   https://bugzilla.mozilla.org/show_bug.cgi?id=2043895
+ *   https://github.com/TeamPiped/Piped/issues/4238
+ */
+if (
+    typeof navigator !== "undefined" &&
+    /Gecko\/[0-9]/.test(navigator.userAgent) &&
+    navigator.mediaCapabilities &&
+    typeof navigator.mediaCapabilities.decodingInfo === "function"
+) {
+    const orig = navigator.mediaCapabilities.decodingInfo.bind(navigator.mediaCapabilities);
+    const cache = new Map();
+    const mimeOk = mime => {
+        if (!cache.has(mime)) cache.set(mime, MediaSource.isTypeSupported(mime));
+        return cache.get(mime);
+    };
+    navigator.mediaCapabilities.decodingInfo = function (config) {
+        if (config && config.type === "media-source" && !config.keySystemConfiguration) {
+            const v = config.video;
+            const a = config.audio;
+            const supported = (!v || mimeOk(v.contentType)) && (!a || mimeOk(a.contentType));
+            return Promise.resolve({
+                supported,
+                smooth: supported,
+                powerEfficient: supported,
+                keySystemAccess: null,
+                configuration: config,
+            });
+        }
+        return orig(config);
+    };
+}