Doing nearly everything in the game my first time.. maybe 80 hours. Platinum in about 110-115. I haven't done a speed run myself, but something close to it.
I have a friend that plays co-op with me. All we do is try to go through the game, both of our games, as fast as possible. We got through the first new game in maybe 30 hours total, for both of us. This included both of us upgrading weapons, gathering spells, maxing out some covenants to get miracles, upgrading armor, etc. If you took out the time we took to text talk, and time waiting to see each other's soul signs, I bet it would be closer to 23 or so hours, so go through the game essentially twice, gathering all items and sorceries that we needed to take into NG+.
Never glitched though.... I'm sure that chops off about... oh 75% of the entire game?