Device: Macbook Pro 2017
Operating System: High Sierra
I've been organizing my music into genre playlists recently. To do that I have an 'unsorted' playlist, which I remove songs from when I put them in a particular genre playlist. To do so, I filter for the song name in 'unsorted' and then select the 'Remove from this playlist' option in the '...' menu. Each time I do this, the operation gets slower (seemingly exponential growth--not sure about that but definitely superlinear, also definitely somewhat stochastic). Memory use doesn't significantly increase even when the operation takes ~5 seconds; however CPU usage hops up to around 15-20%, rather than its normal (playing music) level of 1-10%.
This issue isn't preventing me from doing anything, but it could indicate a deeper inefficiency in how you're removing from playlists. I haven't looked into the effect of filtering vs not on the performance, nor the relationship with playlist size--though my 'unsorted' playlist is pretty large at ~3,000 songs.