I'm a MT Sith Juggernaut for my guild and I can say that the GCD bugged is NOT caused by parry/dodge/deflect, but it does LOOK like it does. I can pretty much say that this is a general bug because I've had it happen rarely on my non-tank characters because I'm OCD and hit the buttons repeatedly. 1. I've had the GCD bug happen several times on the Soa fight in eternity vault, in this fight this boss does NOTHING you can parry/dodge/deflect (Verified by the fact that retaliation NEVER triggers) 2. I've jumped into large packs in HM's and had zero issues firing off my abilities, and when you're rolling with around 30% defense jumping into packs of 3-5 it's almost impossible to NOT parry/dodge something. I can tell you the main thing that helps me avoid the GCD bug is DO NOT SLAM YOUR BUTTONS. This is extremely difficult for me since I'm fairly OCD and want my abilities to fire as fast as possible. Honestly it looks like the problem is more in the ability queuing system over parry/dodge. To give an example, my normal opener on trash packs in HM's was to Force Charge->Smash and I would be slamming my smash button frequently while force charge was still executing, and a LOT of times I would end up GCD bugged. Now I do my best to hit charge, then right before the GCD is done I hit my smash button ONCE and just try my damndest to leave the button alone. This seems to solve almost all of my problems. There's also a sync issue with the client/server where you won't actually be where the server thinks you are, and you'll try to fire off abilities but can't. This can be seen pretty frequently on mobs that like to stun/choke you on their first action if you use force charge to open. You can solve this by using force charge again, or having a friendly sorc use their grip ability on you (Intervene doesn't seem to work as well for fixing this issue).

This fight on hard mode is currently bugged to hell and back. When HK-47 goes into the center core you will need to disable 4 pads on the actual core itself. Failing to do this will grant him a power of the core buff which will drastically buff his damage, and he will fire off a suppression burst as soon as he comes out. This is a cone AoE and any non-tank hit by it is pretty much borked. His snipes on hard mode hit a jugg tank for around 10k a pop, so he will be one shotting a good chunk of your group. The bug currently is that hitting the 4 pads on the center are hit/miss. Sometimes it works fine, other times it'll just ignore the fact you hit all 4 of them and give him the buff anyway. So far I'm not impressed with hard mode flashpoints, almost every one of them seems to have crippling bugs with the exception of Black Talon. Still have 2 more to try, but I'm not optimistic about it. Boarding Party hard mode was fun but not being able to loot the last chest was bohockus.

Well my other suggestion for getting it to run well on lower end systems is to turn bloom off, this had a huge performance impact in beta for me as well. Haven't tested on retail since it kept all my settings from beta.

Turn shadows off. Not low, OFF. This will probably solve all your problems alone. I have a laptop with worse video card then that and once I turned shadows off it runs pretty fine now.

1st - Send to imperial intelligence 2nd - Execute 3rd - Torture Will get all the "right" answers.