My approach to this is to help people who are in combat once the gate opens (if I am the only one wanting silver chests I'll just suck it up and move on). If i see people sitting on the gate I simply inform them the run will be faster if they help. If they continue to sit on the gate while other people are looking for silver chests or whatever, I simply ignore them. Their hunger for a speedrun is actually slowing them down, so I get a chuckle out of it. Speedrunners are the ones who should be forming premades, since if they want a fast run it makes more sense to queue with 3 other like-minded people.