Fastest fps game?

hello i like to play counter-strike source but i get so bored becaue it is so slow, and the deathmatch is a bit better but it is stil slow i wnat a really really fast fps game where u are bombarded with enemies and attacks and u need fast reflexes because i have fast reflexes but also i have "adhd" so after a few seconds during a round in CS:S nothing happening i lose concentration and i get kiled :( and if i rush in aggressively i get killed and have to wait :( i am thinking ut or something which game and which version shoulod i get, i want one where i will always find a game, not one which no one plays and the only server there is always full or something :(