On a PC with with NVIDIA RTX 5060 Ti 16GB, a 4min live recording with drums, bass, vocals, piano and guitar, Unmix Song at “High”:
SL12.0.10: 1m 28s
SL12.0.20: 1m 11s
One thing that seems different is that the dialog box at first appears blank, and only after about 15 seconds the progress bar appears. If I time the process from when the progress bar appears, then it only takes less than a minute, so about 4 times faster than realtime. Nice!
I also notice in SL12.0.20 that the GPU RAM is now completely utilized and that the GPU usage is up to about 70-80% on average throughout the process.