Identify perfomance bottlenecks in Backend

[claasga]

Description

Currently, Exercises with 100+ Patients or several exercises can become quite slow during the exercise. Additionally we want to find out for future development if our Database-IO-heavy backend architecture is viable for the future.

AC

• Find out maximum possible exercise sizes
• Find out maximum possible Actions-per-second
• Identify performance bottlenecks (e.g. by profiling tools cPython & Django-silk and visualizers)

[Toni000]

At least part of this was done by Jojo in #339