Seems to be a Server issue, when playing “EU West” MS performs very badly, like it totally skips the 5% note from it’s own tree, and channeling Flurry doesn’t get Attack Speed Bonuses, playing on “US East” or even “Some Asia” regardless of the slightly worse ping to the server, the skill performs waaaaaay better, so basically the more people are with you on the server the worse the skill performs.
I have 30-40ms in EU West and still have problems and that 5% note does nothing anyway. With or without this note its bugged.