Accelerate startup by caching tags

When starting up Mp3Tag with a few thousand files, it takes at least a few seconds to start. What about adding an option to write (maybe only the most important) tags into a cache file and then load it on startup and refresh in background (maybe with a little progress bar at the bottom)?

I rarely modify my tags outside of Mp3Tag, so it would work great in that aspect.
It would also help people who have their music collection on a network drive, or, like me, use a SSD internally but not for the music collection.

see also this discussion: /t/19265/1