Client keeps lagging and malfunctioning

I uninstalled the client back in October and reinstalled it last night. I played for the first time today in months and came across 2 major issues affecting my gameplay. The 2 issues I am having:

First is latency issues. I had this back in October and was a major reason why I uninstalled the game. Randomly the game will just lag a good 2 seconds behind. It happens in team fights but also when at the start of a game when I am buying. It happens randomly in lane when I am CSing or when I am roaming on my own and just placing a ward in a bush. I do not think it is an overload of stuff happening on screen because it just happens randomly. It's good for 10 or 15 minutes and then lag slows me down. I cannot play a game without it happening at least twice. And this happens even when I am home alone with sole ownership on the internet.

Secondly, and this is a new one, randomly the game just stops recognizing my inputs. Sometimes my clicks still function but only to signal stuff on the map, like the control key got stuck or something. I inspect the control key to see if it is indeed stuck and it is not stuck. Other times nothing works. I cannot use abilities, I cannot click, I cannot use the chat, etc. Alt + tab does sometimes reset it back to normal, but that only works half the time and even then it takes a good 5 seconds to tab back the game screen again which is a death sentence in a team fight.

It's only with League of Legends that I have any of these problems. Overwatch works fine, CS:GO works fine, GTA V works fine, Farcry, Rocket League, XCOM 2, 7 Days to Die and all the other games I own which are far more demanding that League all work fine. I'm baffled why it is giving me so many issues on a laptop that was a major improvement over my old set up.

What is the fix? The specs of my new laptop are exactly like whats in the link below. I haven't updated anything since purchasing it.

https://www.newegg.com/Product/Product.aspx?Item=N82E16834316384