Historically, interpreted languages have been much slower than compiled languages. For example, a BASIC interpreter has to parse each line each time it is executed. Java compiles the source into byte code. The overhead of interpretation is the time it takes to look up the byte code and find the right subroutine. On some architectures, that may be very small. The other overhead is that of the run-time checking of the operands, which is not, strictly speaking, an interpretation problem. The byte code keeps the parsing costs low, so that Java code is only somewhat slower than native code. However, that somewhat slower is in the range 1.1 to 10 times slower.
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