GPUImage.saveToPictures blocks UI with preview

MainActivity

// in onCreate()

glSurfaceView = (GLSurfaceView) findViewById(R.id.surfaceView);
mGPUImage = new GPUImage(this);        
mGPUImage.setGLSurfaceView(glSurfaceView);

// on user button click

mCamera.mCameraInstance.takePicture(null, null, new Camera.PictureCallback() {
    @Override
    public void onPictureTaken(byte[] data, final Camera camera) {
    	
    	camera.startPreview();
    	
    	Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);
    	
    	// GPUImage.saveToPictures blocks UI and view goes black for up to 5 seconds when saving high resolution picture
      mGPUImage.saveToPictures(bitmap, "GPUImage", null);
    }
});