Build a High-Performance Flutter Story/Reel App with Firebase & Advanced Pagination

I need a Flutter-based story-sharing app (similar to Instagram Reels/WhatsApp Status) with the following features:

I already have the app made using the story_view package with liking feature but it feels slower and lags play/pause and right/left navigation, so it is upto you if you wish to improve it or would like to make it custom

1) Core Requirements:
Reel/Story Format
Users can upload multiple photos/videos + captions (like slides in a story).
Stories should display in a vertical-scrollable feed (not auto-advancing).
Tap-left/right to navigate between stories (like Instagram).
Play/pause functionality for videos.
Like button on each story.

2) Ultra-Fast Pagination & Loading
Critical: Implement efficient Firestore pagination (load first batch on app start, then lazy-load more).
Optimized Firebase Storage for fast media retrieval.
Pre-load next stories without lag.

3) UI/UX Enhancements
Top toggle arrow to switch between "Latest" and "Popular" stories (sorted by likes/views).
Replace story_view package with a custom, high-performance solution.
Smooth transitions between stories.

4) Firebase Integration
Cloud Firestore (for story metadata).
Firebase Storage (for media).

5) What I Provide:
Existing code for:
Story upload screen.
Current story_view implementation (to be improved).

Deadline: Saturday (urgent)