Hi @Roxxor91 and welcome to the Restic forum 
So this kind of behavior has been a topic on here before. Here is a thread where another user also mentioned RAM limitation issues and it was discussed in full there: High Memory Usage on Backup, Prune, and Check
Have a look here is the answers and information there give you a better understanding how restic works and if this solves your question.
I hope this helps you with the issues you’re having - if it does, let me know here so we!