Is bluetooth lag for A/V playback due to SD card?

[Cree]

Ive noticed when playing music and videos over bluetooth from my pinephone, the connection gets a bit choppy. Im sure the PP's processor, wifi and bluetooth are fully capable, so i was wondering if it might be caused by the OS and all programs being mounted on the SD card thereby adding another r/w process in the middle of buffering? If so, i suppose an SD card with a higher transfer rate might alleviate this issue, but so too would using the eMMC for the OS, although my earliest experience led me away from that.