load of my huge library on my new smartphone stops each time i switch to another app?

[nova2nova]

Plan Premium

Country France

Device iPhone XS on iOS 13.2.3

My Question or Issue

Just activated few days ago my iPhone with 256 Go (!) to load my huge library - more than 3,000 titles

I'm surprised it progresses so slowly, stopping each time i switch to another app, even if i keep listening Spotify music...?

Any trick to avoid it and speed up the loading?

Regards,

Hervé