When I'm playing against a computer, it moves virtually instantly. Automatically, I'm speeding up as if trying to match it. Obviously, I'm not a computer, so I make horrible blunders if I move so quickly. When playing OTB against a live player, I take considerably longer for my moves (I'm fine with playing a three hour game) and consequently I play a lot better OTB. By the way, I virtually always play without a clock.
Is this common? Are there any tips besides "just don't do this"?