When Turbosounds and SongBook+ run at the same time, it may happen that Turbosounds shows latency of 23 ms.

But you can avoid that with a few settings:

1) In SongBook+ settings select "Media player", then disable the 5 switches "Allow playback of sound file 1-5".

2) In SongBook+ settings select "Metronome", then disable the switch "Enable acoustic metronome". 

With these settings in SongBook+ the latency in Turbosounds app should go back to 1.5ms or 2.9ms.