Well the thing does talk to you trough telepathy, so I assume you hear what she says in a voice that sounds familiar to you. A voice that your brain comes up with to "translate" the telepathic connection & information that she sends you.
Performance hasn't been looked at much duo to the game being in active development. Soon they're starting a 2-3 month performance pass to optimize the game and fix all those weird graphics glitches and lag events. Worry not it's on their radar.
I recently purchased early access with the steam sales as I couldn't wait any longer to try out this gem of a game thanks to the many youtube videos of people trying it out.