90-100% CPU Usage Main Menu

[bobgrey1997]

I recently bought a new PC which should be easily capable of running this game:
CPU: AMD Ryzen 5 5600X 6-Core
GPU: RTX 3060 12GB
RAM: 32GB DDR4 3600
Storage: 1TB M.2 2280 NVME SSD

I have been playing games such as Cities: Skylines, Cyberpunk 2077, and Stellaris for the last couple weeks with no issue. Today, however, I try to launch Stellaris, and am greeted with unplayable lag. After a quick investigation, I find it is using up almost all of my CPU usage, even on the main menu! At first, I thought this might have been a heating issue (not much in the way of cooling in a Freightliner truck), but even after letting my PC cool for an hour or so by turning it off, the issue remained. CPU temps seem to fluctuate between mid-40C and mid-70C, so I don't think that is the issue (even at mid-40. the issue remains). That then led me to mods. I made a playset which has no mods (a Vanilla playset), and the issue still occurs.
What is going on?

I hope someone here can actually help, as every thread I found online is just dead, with no hint of a solution beyond a virus or Steam Overlay (I have Overlay disabled, and I rarely have internet through which to download things, so a virus isn't exactly likely).

 

[bobgrey1997]

Huh, well...
YAY, technology!
I seem to have gotten it fixed. The issue seems to have been relating to my graphics card instead. I go to check my NVidia Control Panel, as it has the exact GPU specs (I always forget the numbers and such) so that I could list it in the previous post. Unfortunately, it was not showing up when I right-clicked my desktop background, and opening it via the Start menu just... wouldn't open it.
After making the previous post, I go to try updating Windows, thinking maybe one of the times I was connected to the internet (which isn't often, because trucking), I had an update that broke something, and maybe they released another to fix it. While checking for updates, I went over and checked my graphics drivers as well. To my surprise, I was running on integrated graphics! I've had this issue countless times in my old PC with it's GT 610, then GTX 760, then eventually GTX 1050TI. Manually searching and installing the drivers from the NVidia site always fixed it, at least for a while (I will probably have to do this every few months or so, or more).
Anyway, with the new drivers installed, I am running on my GPU again instead of integrated, and Stellaris is now running 1.3% of my CPU.