Question about resolution

Ok so my tv says the native resolution is 1366 x 768. I’m hooked up to HDMI 1 so I am in pc mode where everything is disabled. This is way better then 720/1080p for my tv.
Now I can also use 1440x900 and 1680x1050 but it gets put into letter box. When the tv is set to one of these settings I find that a have less lag.

I am on wireless so every bit helps but I swear when playing on 1366x768 when someone has their shield down and I headshot it does not always register. There will often be times when I feel I should have gotten a kill and then I don’t.

When I play on 1680x1050 this is never the case, in fact there have been times when I feel I shouldn’t have won the duel or I’ll trade with someone that I normally wouldn’t have.

Any ideas?

Could the fact the screen gets put into letter box and is smaller have anything to do with this. Both settings look great but I really just care about the least amout of lag