I've been using the feature of Photoshop CC to convert a large number of Nikon raw files (D800 NEF format) and their associated sidecar XMP files to .jpg format for sharing with my family. I select a folder that I want to convert and then let Photoshop process all the files in that folder, writing the jpg file to another directory. The NEF files are stored on an external drive and the jpg files go to a folder on my C drive. If there are only a few files in the input folder I will typically see it take about 8 to 10 seconds to convert each file. The D800 produces 36 mega pixel images. However, I have a few folders with upwards of 200 images. On these larger folders things usually start out OK, but after processing a few tens of files, things slow down dramatically to the point that it takes about 70 seconds to process each file. I'm running on Windows 7 with all updates installed. I've also noticed that if I have the Windows Explorer open and I look at one of the directories involved in the conversion, I can often cause the slowdown to happen. Unfortunately it's not a completely repeatable test case. The symptoms have the characteristic of either a conflict in file permissions and accessing, a temporary deadlock, or maybe an improperly handled return code from an attempted file access. This problem can add hours to a task that should take minutes.