I'm getting weird input lag during combat in Far Cry 6 on my MSI B450M, is it the motherboard?

While sneaking through the jungle, I noticed my mouse clicks felt 'floaty' and delayed, which is a death sentence in a firefight. LatencyMon revealed that the USB controller on my MSI B450M Mortar Max was spiking DPC latency up to 2.6ms, causing instant frame drops. I tried moving my gear to USB 2.0 ports, but that capped my polling rate at 125Hz, which is useless for gaming. I eventually went into Device Manager, disabled three unused USB ports, and used a tool to manually reassign IRQs for the NIC and GPU. After the reboot, DPC latency dropped below 0.7ms, and the lag completely vanished. I accidentally messed up the audio controller config during the process and lost sound for a bit, but a service restart fixed it. Chipset temps are 42-50℃ and RAM is 38-42℃. The response time is finally back to normal.