Java while I no longer use it day to day in my job. Is not slow at all. Especially with Java 8 and the introduction of more functional programming methods. It's become quite fast and easy for a beginner to learn. Its uses are also tremendous, you can use it to make GUI desktop applications, back end for websites with JSP, native Android is written in Java. Not sure how much experience you have with this field but ti doesn't seem like much.