Tag to Tag Conversion Taking Way Too Long

I name my files by the track title and noticed that in the Title field they are all empty. So I decided to fill these in by using tag to tag conversion. Taking the Filename and also making it the Title. Well, after an hour it had only managed to convert 14 Titles. Why does it take so long, and how can it be made to go faster?

To import data from filenames, the first choice would be Convert>Filename-Tag.
To be honest: I bet that this is something local.
So it could be that you have the files on a NAS. Or that the files are really big and have to be copied between the PC and an external storage.
Or that you have another program running that tries to access the same files.
Things like this.