The use of mobile phones has increased a lot in recent years. At the same time, it has become more important for apps to be fast, efficient, and have good performance to attract users. Apps can be developed either as native apps, which work only on a specific operating system, or as cross-platform apps, which work on multiple operating systems such as iOS and Android.

This thesis compares the performance between native and cross-platform apps. Kotlin is used as an example of a native app, while Flutter is used as an example of a cross-platform app. The study will compare their performance in different scenarios, focusing on e-commerce-related functions such as product sorting and database operations. To evaluate performance, CPU usage, RAM usage, and execution time will be measured.

The method consists of several steps. First, five e-commerce apps were selected, and functions that appeared in at least three of them were identified. These functions were tested five times on two different phones. CPU and RAM usage were measured using Android Profiler, and execution time with built-in functions available in Kotlin and Flutter.

The results showed that Kotlin generally performed better in database operations, especially on the newer device. Flutter, on the other hand, showed stronger performance in visual tasks like scrolling, sorting, and animations. The conclusion is that no framework is best in all situations. The choice of framework should be made based on the app’s main needs.