Very Poor Optimization

Bungie Account name: timelimiter#3924
Platform: Steam

Been trying both yesterday and today to play this game (which I've been eagerly awaiting for about a year now) and so far, in 30+ attempts to get through the tutorial, I have played approximately 6 whole minutes of Marathon. Overall, very disappointing. 

I know this isn't a network or connection issue, since I've been mostly plugged into an Ethernet connection receiving around ~850 or ~900 Mbps in all these attempts. For all of my (only) 113 minutes logged playing on Steam on this i9-13900, NVIDIA GeForce RTX 3050 6GB, 16 GB RAM computer, those 6 minutes of gameplay have only come from when I windowed my game. There, I was getting a solid 40 FPS compared to the full-screen average of 8 FPS.
My CPU % was hitting anywhere from 40-80%, and my Memory % around 95%. This is with the game settings and visuals changed to be less high or taxing. I have considered it's just an issue with running Windows 11, but...

I already have the Deluxe edition preordered, but if I cannot manage to play a game to test out and see if I truly like it I will simply rescind my preorder payment. It'll hurt terribly, since I've been waiting for this game for about a year, but what other choice is there if I cannot actually manage to reliably boot up the game on the only platform I can play?