The actual numbers shows that it works because there are no real concurrent request at database/ server level. 4GB Ram and 2 cores should be a size where you dont get any problems
The required ressources are related to your scenarios. I. E. Exam quizzes with 50+ students starting at the same time, huge scorms or ectensice use of chat will need more redsources than your data center gives you in the moment.
Ralf