FPS drops in raids

So I have a really weird problem where when I join Raid Finder and try to kill a boss, my FPS drops to less than 5. It doesn't happen in dungeons and never happened when raiding in cataclysm. Its just as soon as the tank pulls the boss in a raid my FPS drops to >5 and its becomes unplayable. I don't know if the problem is on my end (hardware issue or software issue) or whether its at Warmane's end. I was just wondering if anyone else has had this problem and has a solution. The FPS drops hit hard on Tsulong in Terrance of Endless Spring and Jin'rokh the Breaker in Throne of Thunder.

PC Specs:
CPU - AMD FX-6100 6 CORE
GPU - GTX970 4GB DDR5
RAM - 8GB

Addon List:
- Deadly Boss Mod
- Dominoes (UI changing addon)
- HealBot
- Recount

PLZ HALP MEH PEEPLE

I have the same issue, when I join RF or any 25 raid group my FPS drops to 7 and below, I reached the conclusion that it is because of the server, mainly because it didn't happen in retail.

I never had the problem when the server was on cataclysm and my rig was terrible back then. It's just really weird how it's only on Raid Finder and only when pulling a boss.

For me it happens the whole encounter and it really annoys me, because it´s unplayable, sometime I cast 2 times the same spell and it is hard to follow boss mechanics. It´s very strange because when I was playing retail I had +60 FPS in RF and 25 man raids. Also here in warmane when I´m doing bgs or places with a lot of people I´m still playing with +60 FPS.

Yeah exactly. Everywhere else in the game, including battlegrounds and when a fraction raids a capitol city I'm still 60+ FPS. It only occurs on boss encounters during raids. Its very strange.

I to suffer from this problem, 60FPS until boss pull. I was fine in Cata but in MoP its unplayable.