Are you trying to do Praetorium to get your storyline win?

A lot of people speedrun Praetorium using 1x tank, 1x healer, 6x dps. If everyone is decently geared and knowledgeable about the fight, that's really all you need. Duty Finder forces you to use the 2x tank, 2x healer, 4x dps setup... so the only way to organize a speedrun is to completely build it with eight people. Very few people join a DF group unless they actually need the storyline win.

Anyway, I think that's why your queue might be super long... or perhaps you should try requeuing?