I second using Python and a framework like Flask. If you're already comfortable in Python, you'll be able to get off the ground faster, and be productive sooner

I second using Python and a framework like Flask. If you're already comfortable in Python, you'll be able to get off the ground faster, and be productive sooner. I would leverage a JS framework on the front end, as that will definitely improve the responsiveness. Perhaps something in React or whatever is the currently vogue framework. For drawing and graphics, D3 is really powerful and will help you avoid having to write all the drawing routines from scratch.