i7-5960 cpu, gtx980ti, 64mb of 3000Mhz ram, SSD drive for mediacache, windows 10. It can't be hardware limitations...
Why can't After effects manage to make any real time playback so you can preview and edit nicely to music. Even just simple sequential tif runs (3d renders as sequential tifs) will not ever playback at real time, even just a few seconds worth cannot build and playback from ram. There's masses of ram available but AE just will not get above stuttering sound at 23/24 frames per second to reach a 25frame per second realtime playback rate. No matter how simple or complex the projects layers and effects.