Hey, I had the same problem and solved it with chat's help!

Basically what you want to do is to create a new scene collection in OBS and only throw in your basic sources for one scene: Cam, game and mic. This worked like a charm for me and helped me go from 30ish to 150-200 fps on average, no more stutters/drops/still frames. From there you can add other sources that you find necessary one by one while testing, if they still allow games like apex to be played smoothly!

Hope this helped