TTK to low? No bad server performance!
You must have noticed that it takes you 1 to 2 seconds to kill a player, but your opponent only 0.5 seconds.
From your opponent's perspective, you need only 0.5 seconds and he needs 1 to 2 seconds for a kill.
You probably also noticed that you get the bullets when you are already behind the cover after sliding.
From your opponent's perspective you are still in front of the cover and the bullets hit properly.
There are many more examples...
Anyway, it's not because TTK is too low, but rather because of the slow calculation time of the servers. What is already over for the opponent, just happens for you.
In the worst case, you are already dead for the opponent before you even perceive the damage.
In 1 vs 1, if I see the opponent is about to target me, I'd rather take cover and flank him or pull the dozer shield, tag the opponent so someone else can kill him. I avoid 1 on 1 and try to kill opponents mainly from the side/back. (Play in PC only lobbies)
That the TTK are dependent on the level/playtime or ingameshop purchases, I have not noticed. Something like Pay2Win or Pay2EasierLobby I have not seen here.