Create a search bar at the top of every playlist to make it easier to retrieve music from a playlist you have created. This is seen on the Local Files tab, but not on any other tab. In the previous version of spotify this was present on the starred tab as well, but for some reason it was left out of the new layout. Please bring it back or add a search box to the playlists.
You can already bring up a filter for every playlist, by just pressing Ctrl/Cmd + F
Then you can filter all the songs inside a playlist. ;)