Optimize Mobile App Performance

My current mobile app does everything I need function-wise, yet it feels sluggish in day-to-day use. I want a set of focused, low-risk tweaks that tighten up speed and overall responsiveness without changing the core experience people already enjoy... (Budget: $15 - $25 USD, Jobs: Android, Flutter, iOS, JavaScript, Mobile App Development, PhoneGap, React Native, Software Testing)