Queue times have been super janky for me. In my experience, solo queues are almost always a little faster just due to being able to get a queue in progress. I've found having a full group can often give the same queue times as solo queuing. I've had some times where i've 2-5 man queued and it took 1 hr+, and at least a few times where i've had insta-queues with the same group. Before 2.5 with a full group I usually had 5-10 min queues and another over 10 mins was rare, now it's more like 20-30 mins avg queue (Aether Adders) depending on the time. The main issue with having a group queue is if one person doesn't click you all don't get in the game, so it helps to have reliable people.

A huge part of it is when you queue and how popular your GC is. From the sound of it, your GC sounds like it's not very popular if they're losing that much, so in that case queuing with a full group could substantially lower your queue times (as you're providing more people for your GC) and you might even get insta-queues on secure if you get a 24-man.