Hey Thomas, so sorry about the late reply but Itch flagged your post as spam for some reason :(
To control speed you can tweak advanced settings (the icon with the sliders) for the models.
Chatterbox: Increase "Exaggeration"
OmniVoice: Increase "Speed"
Kokoro: Increase "Speed"
The other models don't have a way to directly influence speed. I'm working on adding post-processing directly within VCP so you don't have to swap programs.