Does use of final keyword in Java improve the performance?

Performance aspects of final

The realm of thread safety

The use of final fields guarantees cross-thread visibility post-object construction, vital for immutable objects shared across threads. While this is about thread safety rather than speed, well-synchronized programs naturally perform well.

public final class Configuration {
    private final int timeout;

    public Configuration(int timeout) {
        this.timeout = timeout; // As constant as the laws of physics
    }
}
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The Configuration timeout is visible across threads after construction—Godspeed Java memory model!

Inlining and constant folding

Final enables potential JVM optimizations like method inlining and constant folding. However, Java's Just-In-Time (JIT) compiler does most of these optimizations at runtime based on the program's execution context.

Class design positives

Utilizing final on classes prevents inheritance, which can lead to more readable code with clear design boundaries. This can hint the JVM for possible class initialization optimizations.

public final class UtilityClass {
    // This class stands strong and independent, not to be subclassed. 
}
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Local variable performance

Local variables labeled final get special treatment from the Java compiler. Regardless of the JVM not having an opcode for final, the compiler forms more optimized bytecode bypassing certain store-load sequences where necessary.

Preventing subclassing

A final class tells the JVM subclassing is prohibited, which warrants method invocation free from override checks, potentially speeding up execution.

Comprehensive usage

Code maintenance benefits

The appropriate use of final boosts code maintainability by signaling clear developer intent. This can reduce bugs that may arise from unwarranted changes to values or classes.

Importance of benchmarks

Benchmarks should always be used to measure the performance impact of final. Performance boosts often depend on the context, and some optimized utility code can see more measurable gains.

// Use benchmarks to understand if `final` changes the game in your unique context. 
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Streamlined debugging

Another aspect to consider is debugging. final helps minimize the amount of conditional debugging checks, which can streamline your code in production environments.

Garbage collection efficiency

The use of final variables can also help reduce garbage collection overhead. Immutable objects require fewer "protective measures" during garbage collection.