Hello Zoltan, and thanks a lot for your answer!
I'm using several programs while streaming, for being able to capture different mobile-device-cams etc. But most of the RAM and the CPU is used by Resolume - about 40-50% of CPU and 2.5 GB of RAM. I have to admit that I'm using quite a lot of images, large videos and also many effects, so I might have overdone it
Sometimes OBS takes as much on CPU, but much less on RAM - just 250-500 MB. While testing now I had a CPU usage of ~5%, so this looks good to me right now. I'll keep an eye on that...
Have you tried direct output capture in OBS instead of NDI?
With this you mean "Fullscreen", "Window" or "Advanced"? I always used NDI, so I need to check this out. Is there a quality difference between those outputs?