Insane Lag Issue

Does anyone know of any way I could fix these terrible lag issues I have had with CoD ever since MW2? I have good internet, hell, I'm even connected via ethernet cable. Ever since MW2 came out, I haven't been able to play because I lag horribly. Now I'm trying to play the Black Ops 6 beta and I'm having the same issue. Nobody else I play with or against seems to be lagging, so surely it's not a server issue. I preordered BO6 hoping it would be different. I genuinely want to play. I don't have lag issues with any other game, so it's definitely something wrong with CoD. I am really hoping someone has any idea of how I can resolve this lag issue.