Runs on JVM

Consider efficiency and optimization as factors for a language to be well performant. Scala utilizes JVM for this. JVM uses Just in Time (JIT) compilation, adaptive optimization techniques for improved performance. Running on JVM makes Scala interoperable with Java. You've multitudinous libraries available as tools for reuse.

If anywhere in your mind you're comparing Java and Scala's performance, let's get it clear. Both Java and Scala programs are compiled into bytecode. JVM understands bytecode and runs it for you. So it mostly depends on the way you write a program. Scala blends in some syntax sugar, compiler logic that can cause your program to be more/less performant than Java. Mix-ins using traits can be an asset to your program architecture but may affect your program's performance. But alternatives in Java may cost the same or more. So it is more about your core understanding of constructs and how your code is going to compile and perform. It takes some time and effort to understand so the choice is yours; as a smart programmer, you may go for a syntactically powerful language.