Mariusz Stanisz
Software Mansion, Senior Software Engineer
Mariusz Stanisz is a Senior Software Engineer at Software Mansion, where he focuses on React Native performance and brownfield integrations. He authored a blog post included into React Native documation for the new Performance Panel introduced in RN 0.83, helping developers understand and diagnose performance issues in their applications. Mariusz previously spoke at App.js 2024, presenting "Brownfield Integration – Exploring the Limits," and later led a React Native performance workshop at App.js 2026. He enjoys sharing practical techniques for finding performance bottlenecks and believes that many React Native performance issues originate in React itself rather than the native layer. Outside of software, he's also a licensed Kraków city guide and is currently building an app to help people explore the city.
React Native: Performance Analysis & Optimization
Handling massive, heavy lists in React Native is a notorious bottleneck when applications scale to enterprise levels. But before fixing code, you must know how to measure it.
Driven by the exact engineering patterns we use at Software Mansion for large-scale products, this hands-on workshop teaches you how to diagnose and optimize list performance at scale. We will start by mastering tools like Flashlight, the React Native Performance devtools panel and the Profiler to pinpoint the root causes of UI lag. Once we isolate the bottlenecks, we will take a heavy, unoptimized application and rewrite its list architecture together.
Key Takeaways:
- Using Flashlight and DevTools to find the exact root cause of stuttering instead of guessing.
- Choosing between FlatList, FlashList, or Legend List based on memory constraints at scale
- Fine-tuning component recycling and cell layout stability to prevent layout shifts during fast scrolls and junks.