My friend and I opted to do the trek without porters or guide, we had backpacks of about 15kg each, after the third day, we were more or less accustomed to the load. Depending on your load or budget or goals, you can consider hiring a porter.
I had 13kg pack then without water.. met a Japanese guy on the 2nd day of the trek and we travelled as a group thereafter. He just had a daypack and it weigh no more than 6kg, but he doesnt have cameras or any luxury items... we were slower than him all the time and he is 20+ yrs our senior, at 50+. So i learnt my lesson then to reduce non-essential weight as much as possible.. on my next trip, I plan to carry a 10kg pack at max... so that I can enjoy the trek... anyway.. a better gauge would be the pack as a percentage of your bodyweight.. at 13kg, it was 20+% for me.. a bit on the high side i feel...