Rockz1) demo playback (for POVs) executes class configs, so you need to change lerp there
i can suggest using mat_queue_mode 0 and forwarding the demo on 0% speed (fast forward is smooth fyi)
2) also having high ping or low fps while recording the demo somehow gets written into the demofile, but the first point should make it much better
Just tried mat queue mode and changing the lerp in my class config and it still feels stuttery, fps and ping aren't an issue