If you are a long-time Cakewalk user migrating to REAPER (perhaps for its lower CPU overhead or superior automation items), the first thing that hits you is the "culture shock."
REAPER will run 300+ tracks with heavy VST3s on a mid-tier laptop. Cakewalk (due to its legacy codebase) will struggle at 150 tracks. The theme does not impact performance, but the underlying DAW does. reaper cakewalk theme
Head over to the REAPER Stash today. Search "Cakewalk," download a theme, and spend 10 minutes tweaking the toolbar icons. You will be surprised how much faster you mix when the UI disappears and the music takes over. If you are a long-time Cakewalk user migrating