I have an application that allows the user to process several Tiff images - ocr, save, select next image, ocr, save and so on. My question is, would you  recommend opening a single global instance of the ocrengine that is used to process all the images (assuming that only one thread is going to use the engine) and close it down when app is closed, or to create a new one each time an image is ocr'd.

I am currenlty doing the latter but I suspect that instantiating a new ocrengine for each image processing step is quite time consuming.

Some feedback would be welcome