Terrible CPU Lag Spikes from UEFI BIOS Settings

I was encountering constant CPU-related lag spikes for the 0.3 update. However this was not the case last time I played from the 0.1 patch with no significant changes to the PC's hardware. I tried troubleshooting it, and now I believe it was me switching my BIOS settings from CSM to UEFI.

[Bug or Issue]
Consistent lag spikes (not network related) where my CPU response time increases dramatically, ranging from a fraction of a second up to maybe two seconds. The DRIVE and SHADER bars occasionally increase when this happens.

Video of the issue and the performance after fixing:
https://www.youtube.com/watch?v=RGV-USxlfzQ

[CPU Lag Spikes Fix]
- Changed my BIOS UEFI/CSM Mode setting from UEFI back to CSM

[Attempted Fixes that Didn't Work]
- Changing chat channels
- Disabling Sound
- Reinstalling the game
- Graphics driver update
- CPU C-States disabled in BIOS
- Options > Sound > Channel Count > Low

[Why I Changed to UEFI]
UEFI and Secureboot are required to upgrade to Windows 11. I never planned on doing this until I wanted to try out Battlefield 6, which required me to change these in my PC BIOS settings.

Turns out Secureboot was already on. I had to do some work on my hard drives to re-partition them in some way to be able to boot in UEFI mode.

Update 0.3 arrives, and the performance has become increasingly terrible as I played through the campaign.

[PC Specs]
OS Name: Microsoft Windows 10 Pro
Version: 10.0.19045 Build 19045
Processor: 12th Gen Intel(R) Core(TM) i7-12700, 2100 Mhz, 12 Core(s), 20 Logical Processor(s)
GPU: NVIDIA GeForce RTX 3070
Board: MAG B660 TOMAHAWK WIFI DDR4 (MS-7D41)

[Conclusion]
It's hard to say whether this is strictly an issue with my hardware and software, or if it's an issue with the client. Regardless, I just wanted to post it here for documentation's sake and so I can link this to related forum posts as I share my findings.