There is probably something weird with your setup, I get full frame rates in OBS on my 2015 macbook no problem.
NDI feeds over the network so please make sure no firewalls are blocking it and try out the NDI source’s options in OBS. ( there is a drop down experimental low latency mode that works very well for me)
Please also try out Newtek’s “NDI Video Monitor” from their official NDI Tools
Please use the obs thread to follow up on this so we can keep all the info in one place: Using Hypno with OBS