hello, I have a question which java bytecode does kotlin compiler targets per default? java 6? does it make the compiler faster if I say I target java 8? with

compileKotlin {
    kotlinOptions {
        jvmTarget = "1.8"
    }
}

our android app supports min android SDK 21

Java 6 by default

java version also doesn't matter unless you use specific features that require SDK24 like default interface methods in Java. Doesn't affect Kotlin at all though.

With sdk24 and java you also can use @JvmDefault annotation, but this make sense only for compatibility with some java code usually useful only for libraries and java interop