Hi @Dawid,
Native apps work faster than PWAs (web versions).
By the way, you can build and test your app in TestFlight (iOS) and on Android before publishing.
Of course, there are many factors inside the app which can affect its speed: using too much lists on one page, many-to-many relationships, non-optimized images, etc.
There is a good thread to read here: Do’s and Don’ts for app speed
Best regards, Victor.