VR newbie!


I am quite new with UE4 and Vr in general. I have bought the htc vive pro and so far love it. I mainly deal with arch viz stuff and design oriented projects. However I am little confused on quite a few issues with regards to performance mainly. I currently run everything through the latest MacBookPro with a egpu RX580 an a sonnet breakaway box. In general I’m quite happy with my macs performance but perhaps I will migrate to something more solid in the future. When I build my VR and play it I get staggering even with nothing more than a plane in the scene. (I know the pro is more demanding than the regular one) but my fps always hover around 70fps - which I guess is below the 90 optimal however I thought my rx 580 would be taking over and getting me a better performance instead I feel that its the gpu that renders this - is this correct ? Is there a way to go higher in fps - I have tried a few of the settings in the editor but have not seen any real improvements…quite confused on how the whole system works…any help appreciated