First you would need both packs to be discharged to compare, so maybe he is not using all the capacity. 3000mah is 3000 mili amp hours, or 3 amp hours (samething) this means its capacity is capable of supplying 3 amps for an hour and vice versa for charging, at 3 amps it will take 1 hour. You cant change that, 3000mah at 3amps will take about an hour, so your charger is about right (might be getting a touch more that 3000mah in them.
If the other charger is putting in 3000mah in 35 minutes then it is not charging at 3 amps, it more likely charging at 6 amps (3000mah @ 6 amps draw or charge = 30 mins)
Hope that helps