You won't be able to speed it up much if at all, it effectively takes about 5 times as long to do OCR on the machine. The option adds a lot of complexity to the relatively simple scan process. Even a very fast PC will take time to OCR a document.
You may be able to improve it, but you would need to change the originals, Major stumbling blocks for OCR include fonts it has issues recognizing, images and colors and handwriting.