Tell me about it, mate. I also had a long and tiring day. I only work three days a week but those days I work are usually brutal. I was on E.R. and my day started out good. By late morning, people started to come in and we were rushing until my last minute at work. When I'm tired like this, I'm in no condition to play. I'll be churning out sub standard performances and I refuse to play when I cannot give it my best.
Back on topic, I used to play on a regular run of the mill monitor. Then one day, I got curious about gaming monitors and did extensive research. I bought a BenQ, the RL2450HT. It's the older version of what Foxhound currently uses. It turned my gaming around for the better. For months, I was stagnant on MW3 at 1.5 KD while playing on the old monitor. I finished MW3 at around 2 KD and I've never been lower than 2 ever since. There is no other explanation to the sudden rise of my KD and the gaming monitor is the only hardware that changed.
Input lag has affected me many times. Sometimes it feels like I am dreaming when I hit the fire buttons and it fires a whole second later it seems. And its not just COD either. Only lasts for about 5 seconds for me.
But then again I love my white controller. Problem is if I go single player on a map and walk away from the TV with the controller sitting on the table, my player will migrate about ten feet by himself. My wife tried to use my controller and she curses cause the player doesnt stop on a dime.