It is certainly true that shanties (or chanteys) are sung a whole lot faster in modern concert/singaround settings than they ever were when used as work songs. As was pointed out in the other thread ("Sea Shanties timing and tempo) linked to above, it's impossible to actually work at the pace commonly sung today. But they're generally more fun to sing at a somewhat faster tempo.

The Boarding Party guys used to say that traditionally, shantymen were paid half by the ship owners (to keep the pace as lively as possible) and half by the crew (to keep the pace from getting too fast). I don't know where they got that particular factoid, but it does make a certain amount of sense.