I think a lot of it is mental. With a new lover, I tend to not cum very quickly. If the women is tight, or just gave me a great bj, I can't last much longer once I'm pumping away. I also think Viagra makes me cum a little slower too. But if I need to slow things down, just start looking at her tattoos or something, a little distraction for 5 seconds may be all you need to return to fucking away. Also, who cares, if you cum and it feels good for you, the women won't complain. Then spend time making out, massage, etc., then do it again!