I understand that even simple problems may seem difficult when you're under stress (being interviewed). I know that I perform a lot worse under those conditions

I understand that even simple problems may seem difficult when you're under stress (being interviewed). I know that I perform a lot worse under those conditions than under "normal stress", as I have to prove myself to someone else and not just to myself. But with that said, this shouldn't be a problem for anyone who have been programming for a year or more.