You can't do that for GIF. Each frame can be composited on top of the last frame (ie. no disposal; this allows storing only the part that changed), so to seek to a random frame you may need to replay the whole GIF from the start.
The reason you can seek to any frame is GIFs tend to be small, so your browser caches all the frames in memory.
The reason you can seek to any frame is GIFs tend to be small, so your browser caches all the frames in memory.