FPS decaying after 25-30 minutes.

[Mogwai]

Noticed that the longer a match goes my FPS takes a big hit and my CPU cooler starts to get pretty warm. Was averaging about 240 FPS before it starts to dip.

System Specs:
Windows 11 Pro
Processor: AMD Ryzen 7 7800X3D 8-Core Processor 4.20 GHz
Graphics Card: AMD Radeon 6950 XT
Ram: 64 gigs

Attached in-game graphics setting. Didn't change any except going to full screen mode.