Originally Posted by
Guran
Well unless Blizzard broke a scientific barrier and ACTUALLY speeds up time, they'll be using the mechanics they have to simulate such an effect. The tooltip states that the everflowing changes in the flow of time affect casting, movement and attack speeds, as well as periodic effects and cooldowns. (Through server side scripts, as Wowhead tells us)
Considering movement speed, CDR & Haste are mechanics already in the game, it would be easy to simply reuse them. (magic resistance, defense & ArP are all still in the game code as well)
And as far as the GCD goes, it's hardcapped in the code as far as I can tell, as I've yet to experience(*) any massive Hasting buff to ignore the cap.
If an ability triggers the GCD, it'll always be 0.75s or longer. Considering Fast + lust = 69%(heh) Haste effect, you'ld need to have 18.35% Haste from rating to encounter the GCD cap on instant abilities.
(*)Single exception being a select few vehicles with a 0.5s CD on a machine gun style ability. But that was literally stated in the tooltip of that ability, so they may have opted to give it an ability-specific CD, without GCD-triggering. This is not the case on the Anomaly fight.
PS: If you do end up deciding to lust outside of the Fast phase, I'ld suggest doing it during Normal, preferably at the start, to maximize the total amount of damage you can gain from it. Lust during Fast may still provide more overall damage though, as it should act multiplicatively, thus granting "39%" boost before CD & GCD issues come into play.