TikTok Fix Pack makes tiktok.com work more smoothly in Firefox. It combines several targeted fixes in one lightweight extension. The extension collects no data and makes no network requests of its own. Fix 1: Smooth video playback TikTok may serve HEVC (H.265) streams when Firefox reports codec support. On some systems this can cause dropped frames, stuttering, or playback instability. The extension reports HEVC, and optionally AV1, as unsupported so TikTok can choose a more reliable codec, typically H.264. Fix 2: No more double audio The TikTok web feed can keep several video elements in the page at once. A hidden or detached video may continue playing in the background, causing overlapping or out-of-sync audio. A built-in watchdog detects these stale players and pauses them. Videos that repeatedly resist pause requests can have their media pipeline destroyed according to the configured threshold. Fix 3: Responsive DMs After scrolling deep into a conversation, TikTok can keep hundreds of messages in the DOM and trigger expensive updates while typing. Off-screen message groups are excluded from layout and painting, while frequent draft writes are coalesced with a bounded delay. This keeps the composer responsive in large conversations. Fix 4: Smoother feed Mouse movement over feed video overlays can trigger unnecessary style recalculations and stutter. Overlay repaints are contained to reduce this work. Settings (click the toolbar icon):

Block HEVC, recommended and enabled by default
Block AV1, optional
Single playback watchdog, enabled by default
Strict mode, pauses other playing videos except Picture-in-Picture
Zombie pipeline destruction threshold
DM rendering hints, enabled by default
DM draft fix, coalesces TikTok's frequent draft writes, enabled by default
DM contain mode, alternative rendering isolation
Calm live region, silences chat screen-reader announcements
Reduce hover repaint, enabled by default
Debug logging for troubleshooting

Permission note: Firefox asks for access to tiktok.com during installation. This permission is required because the fixes run directly on TikTok pages. Choose "Allow" for the extension to work automatically on future visits. Privacy: the extension runs on tiktok.com, stores settings locally in your browser, collects no telemetry, and makes no network requests of its own. TikTok's page continues to use its normal network connections. TikTok is a trademark of TikTok Pte. Ltd. This extension is not affiliated with or endorsed by TikTok.