Long stutters ruining experience

Hey everyone, for quite a while now I have had some issues related to stutters on Iracing and it showed last weekend during the Bathurst 12 hour when I had a stutter which lasted for what felt like over a second where all my inputs were disabled pretty much and screen went black with CPU usage spiking. Now this wasn't as evident when I did Daytona however it was still an issue so I had done some things like CPU core unparking and Turning down literally every single setting to it's lowest yet still this happens and worse still it only happens In these official endurance races. My specs are are a Ryzen 5 5600x, 16gb Ddr4 3200mhz and a RTX 4060 graphics card all on a B450m motherboard however I doubt that matters. Any help/advice appreciated as it's a growing concern for me, thanks in advance.