I myself have a 4th gen PC (i7 4790k and I did not notice any difference from better RAM
The best cpu you could get is a i7 4790k which you might not be able to overclock with this board but even a ryzen r5 3600 is better for workloads due to more cores.
You could get 16 GB DDR3 for 60 € used on ebay but it will only increase the size, you won´t see a speed difference in real life even if you buy better one.
I am not from the Switzerland but I believe the prices are pretty high in Switzerland. If you really want to upgrade go with used cpu and ram as they do not degrade and rarely break.