Is there a performance gain for final variables?

Question

Yeah, the title. Is there any difference (other than design, obviously) when writing final or not?

Answer 1

As Flutter framework is build around immutability, the final keyword is a way to enforce that immutability. So it is help ensure the following of Flutter design patterns.

In other hand , the Dart compiler do some optimizations that would not be possible if variable was marker var

Answer 2

Both "final" and "const" keywords may improve performance and reduce APK size for applications built in Flutter. "const" Widgets have a different lifespan that improves performance.

Using these keywords indeed does some good. Though final specifically may be misleading, and the compiler often knows the variable is never reassigned without the keyword. The improvements might not be worth the time. It is a matter of personal taste

I personally stick to using them, because no matter how small it seems, all performance issues are known to stack up and snowball.