I received basically the same things that happened to you, Earther. I'm on xbox one.
One time, both my friend and I had Destiny freeze on us at the same time. We both activated firefly. I had a hand cannon and he had a sniper. The other guy was still in the game after we had to shutdown Destiny. He said the game just slowed down and almost froze but after a minute continued as normal.
My Stormcaller is not fun to use because of how much the storm grenade drops the frame rate.
I hope everything is solved in the next patch or the following one. I miss using firefly and my Warlock.
I've been experiencing heavy framerate drops as of the last week, as well.
I've only noticed it on my Titan. Particularly in King's Fall and on the Dreadnought.
My 1000 Yard Stare has Firefly on it, as does Smite of Merain (though I have not unlocked the perk yet), but I notice it mainly in combat, and particularly in Court of Oryx. More so as Sunbreaker, or if someone near me is a Sunbreaker regardless of my spec.
I've also had frequent disconnects and framerate drops after sniping kills on multiple targets (Firefly I'm assuming). Noticed this today in KF Hard Mode.
Also experiencing framerate drops and disconnects when taking out my Ghost to see hidden platforms, only during the moment I initiate a jump as the Ghost is being "put away."
Currently playing on Xbox 360. Have never experienced these issues to this extent before until recently. The framerate drops are the most frequent and bothersome, although the disconnects, obviously, aren't pleasant to deal with either, depending on what I'm doing.
Off topic but curious: What's with loading back in with 0 Special or Heavy ammo after a disconnect/reconnect? And why doesn't my Heavy ammo synth work when I use it while dead?