I could not care less what people behind me think. When I see the green light flashing for the next customer I walk away, I was too polite once and hurried my transaction for the benefit of the person behind me and left 120.00 euro behind me , I wont make that mistake again.
I must drive people nuts! I check I have my card, count my cash discreetly and put it away, wait until the screen has gone to "welcome" mode and only then do I step away.