If you are facing slow performance issues with Spotify on Mac, then the first thing you should do is to check the Activity Monitor. If the Spotify Web Helper is consuming a lot of CPU usage, then it might be the reason for poor performance. Try quitting the process and see if it solves the problem. If not, then try restarting the Spotify application and see if it helps. If the problem still persists, then try uninstalling and re-installing the Spotify application.