That is rather slow, I think.
So you have to tell us a little more about the setup of your environment.
Frequent bottlenecks are: storage connected via USB or network, NAS software being slow/interfering, anti-virus programs like Windows defender get nosy
Also, you have to check whether other programs access the files at the same time as they notice a change so that MP3tag access is blocked for some time.
The file type like large FLAC or video files slow down the process.
These would be the buttons and knobs that you can twiddle and tweak.