big cpu consumption

hello,

I have a big problem with cpu usage. when i listen microphone to record
what comes, cpu time is consumed apr. 80% everytime which seems
unnecessary. cpu is P4 2.8 GHz. i have lots of programs which does do as
executable from internet and none of them consumes so much. here is the
code, could ou please lead me to solve this problem?

        AudioFormat format = new AudioFormat(
                 AudioFormat.Encoding.PCM_SIGNED, // Encoding technique
                 8000, // Sample Rate
                 16, // Number of bits
in each channel
                 2, // Number of
channels (2=stereo)
                 4, // Number of bytes
in each frame
                 8000, // Number of frames
per second
                 true );// formatControls.getFormat();

        DataLine.Info info = new DataLine.Info(TargetDataLine.class, format);
        line = (TargetDataLine) AudioSystem.getLine(info);
        line.open(format, line.getBufferSize());
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        int bufferLengthInBytes = bufferLengthInFrames * frameSizeInBytes;
        byte[] data = new byte[bufferLengthInBytes];

        while (true) {

            if ((numBytesRead = line.read(data, 0, bufferLengthInBytes)) == -1) {
                break;//here is the place where cpu is consumed!
            }

            out.write(data, 0, numBytesRead);
        }