Large Playlist Won't Load Saved to SD Card

[a-wg_enz1j59o]

Plan

Premium

Country

 USA

Device

Motorola Moto X4

Operating System

Android 8.0

I recently migrated my Spotify cache to my SD card so I can save my music on there and relieve space on my phones storage. Since this SD card is 128 GB I have plenty of space for music and other junk. Currently, the SD card is formatted for my phone and only has Android system data and the Spotify cache. 

I downloaded all my music to the SD card (excluding my large 900 song playlist) and it works just fine. However, when I attempt to shuffle music from the 900 song playlist it lags or won't load any of the tracks. It will even lag upon changing the song. This can take up to a minute to change. Is there any way to rectify this issue for downloading my playlist and songs to my actual phone will drop the available space to about 1 Gb.