I don't normally have that problem, even though most pussies seem tight. I can normally last at least 30 minutes, more if I work at it (and if the girl I'm fucking hasn't cum yet). Fortunately, even after I cum I usually stay hard, or get hard again within a few minutes, so I can keep going through 2-3 orgasms.
If you're cumming too fast, just slow down until you get yourself under control again.
I had a gf that was into tantric sex, and she helped me learn to keep control - often for a couple of hours - then be able to cum almost at will.
-Ranger