I'm sorry, but you're misinformed. There is no graphics created on the server, it just sends you the data you request and the viewer displays it at the FPS your computer can handle. The 45 FPS on the server have nothing to do with graphics on your screen. At all. Nothing.
If SimFPS drops, everything that needs data from the server (object updates, avatar position updates, script reaction, physics updates) becomes slower, but you will notice that your own client FPS will *not* suffer at all. You can still have 30 FPS on your viewer while the Sim is crawling at a 2 FPS 0.02 time dilation. All graphics is handled viewer side, nothing of that is generated or rendered on the server.
The music stream comes from whatever server URL is set on the parcel, which is almost never a LL server.
Voice comes from the Vivox servers which have nothing to do with music.