Need someone to review (small) project for performance issues


I am currently developing a small simulation (see attached screenshot)
Yet the sim is running on 30-40 FPS and I cannot figure out why. Since this is my very first project I don’t see any chance to figure out the performance issues by myself.

Is there anyone who could review my project and give me feedback about potential issues regarding performance?
This project (it’s rather a simulation than a game) is a christmas-gift for my dad, so the deadline of shipping is 20th of december.

I honestly assume an experienced guy would figure this out within 15-30 minutes.

Thankx in advance,
John F