Railjack: Neptune Proxima missions: Extremely bad performance drop

[Jalakopoksaus]

I recently returned back to Warframe from my ~3 year hiatus and so far I've been loving the Railjack missions...until I reached the Neptune Proxima however.

My GPU is rather old (gtx 970) and I haven't been able to upgrade it (thanks to world wide chip shortage), but it can still give me solid 70+ fps. But for some odd reason every Railjack mission in Neptune Proxima drops my fps down to 25-40, which makes those mission literally unplayable for me because I get eye strain and a mild headache from watching such low frame rate.

Every other Proxima (Earth, Venus, Saturn, Pluto & Veil) gives me the normal 70+ fps.

Is Neptune Proxima just so demanding location compared to every other location in the game or is there something else going on with it?