Video tutorial
https://youtu.be/G4aqz1w8MNg
Written tutorial
I have modified my plex transcode directory to use ram insted of slow sd card
it has led to a considerable performace gain
as pi is too slow to transcode video it has great performace for audio
Note:You should not use it if you have little available ram
everything is ram gets wiped on reboot anyways so it is a great place to transcode
mount your ram by
tmpfs /tmp tmpfs defaults,noatime,rw 0 0
use /tmp as transcode directory on plex