Notice the green in-game frame rate counter in the top right. Stuttering got worse & worse as i played longer until it became very difficult to control the character. Restarting the game temporarily clears this up until it begins getting worse again. People online are saying this is related to a bug with clans and that leaving your clan & playing without one is the only solution at the moment until there is a fix for this. Hopefully Bungie/Vicarious Visions can fix this soon.