Can't read tiny barcode through ZXing library

I have recently made an app to detect barcodes using the ZXing library. It works well but the problem is that it can't read very small barcodes and sometimes delays approximately more than 4 seconds to read it. The size of these barcodes is 18 mm for width and 6 mm for the height on some products. I tried with a Samsung Note 4 device. Is there any way or modify some values in the library that help to read fast for at most 1 or 2 seconds?