In my experience (Back when I used to play COD 24/7) I noticed just like you I had WAYYY bttr games playing with like down/up at like the bare minimum so like 5 down & 1 up for example & yeah I'd have these amazing games ENTIRELY compared to whatever I was doing b4 so yeah in general if you know theres lag comp in a game you interested in playing its always wise to throttle down on the platform your playing on with Bandwidth Allocation (If you still want other devices to have bandwidth but also be sure to uncheck download/upload share access with this method) or Congestion Control. (I only recommend doing congestion control THAT low if you have your own private connection as in either your the only one using the internet OR you have multiple routers & no one else is using the same one as you & here you can just keep share access ticked cause the down/up is already low because of congestion control) But in all honesty is MW3 like legit worth it? I kinda gave up on the COD franchise awhile back cause im kind of a boomer now so my fun CODs was like BO/BO2/MW2 (classic version) & etc