We have 3 components, the app, the library and the audio files.
Operating system, page file, app all on the fastest so the SSD.
The library ( everyone calls it so but it is the catalog) is a database. This is the one doing the hard work when querying, filtering, browsing, etc. your collection. This again on SSD.
Might be the database is cached as well. If so, more memory might help to speed up.
Audio files on a HD.
If you start from scratch, things are horrible slow. The media player has to open each audio file, read all the tags and store this information in the library.
Second time is much faster. All the media player has to do is to compare date last modified in the file system with its equivalent in the database. Had to detect new files as well but I don’t think you are hit by a performance penalty as Musicbee does this quietly in the background.
8 TB in SSD might be a bit too expensive as well at the present.
You can try a couple of tricks like disabling the page file.
If Win starts to protest (running out of memory) you know that adding RAM will help assuming 64 bit Win.
https://www.thewelltemperedcomputer.com/SW/Windows/Win7/TweaksSystem.htm