Lockup during big paste

I used MP3Tag to "Copy" tags from about 5000 files and then "Paste" them to another bitrate set of those files in an identical file/folder structure. After answering the warning about wanting to paste the tag information from the clipboard....blah blah blah, absolutely nothing happened for 45 minutes. The indicator in the lower left on the status bar still said "Ready". After 45 minutes the progress bar popped up and counted off the files and all went well. Using TaskMan I was able to see the program using about 50% CPU through all 45 minutes so I knew it was doing something. Although both of the folder structures were network drives, there was no network activity during the times I checked. Would it be possible for the program to have the status bar indicator on the lower left flash "Processing..." or something during this time? I was almost going to use "kill task" because I wasn't sure if the program had frozen.