Game suddenly stutters

Hey guys, I've been playing a lot of games recently and have ran into a problem now. I was playing on my Acer Predator Helios 300 the other day and everything worked fine. I played Black OPS IIII with my friends and had an average of 100fps ingame. Today I wanted to play the exact same game again and was shocked when I eventually joined the game. It was freezing constantly and stuttering from the start of the game and there was no way I could play like this. My game kept freezing every now and then and was stuttering when for example a vehicle was driving towards me or when I was grabbing a weapon from the ground. My mate spectated me and said even he could see the stutters like it was lag or sth, which it wasnt. I dont know what to do right now since i didnt even know something like that could happen (even teammates seing my stutters). Maybe the Intel Turbo boost isnt working? I've also had stutters when tabbing out of the game while trying to open my brower. It almost seemed like my RAM was overloaded, which isnt sth new considering I have only 8gb of DDR4 RAM. BUT, my RAM was Always at such a high usage and I've never ran into such issues. The temperatures of my cpu were really low ingame compared to what they were before when everything worked fine. I seriously dont know what to do anymore and would appreciate any help!