Duka online is a tumblelog.

Half a second delay killed user satisfaction.

Why speed matters by Greg Linden and Maryssa Mayde

Half a second delay caused a 20% drop in traffic. Half a second delay killed user satisfaction.

This conclusion may be surprising — people notice a half second delay? — but we had a similar experience at Amazon.com. In A/B tests, we tried delaying the page in increments of 100 milliseconds and found that even very small delays would result in substantial and costly drops in revenue.