yes in asian session the market's movement is a bit slow, spikes occurs less in this session comparing to NY session. that's why it is a bit less riskier to trade. but the possibility of making very big amount of pips in this session is also low! that's why i like to trade during NY session because of high volatility. though i don't trade eur/usd when Draghi gives any kind of speech, cause some spike occurs during his speech.