No its not. Not if you have super fast chakram and attack speed. Also whirling blades has a thing where once you hit it , there's a delay in hitting other skills but periphery doesn't have that delay and it seems to actually obey APS with normal chakram. The process rate is not low from what I've tested but then again, I used Epiphany, Angelic and threw every APS thing I wanted for that chakram and whirling blades PvE with Periphery. Idk how good I can get whirling blades in PvP though.
It was a test build however and not a full fledged build. Using periphery (5), chakram, 75% Attack speed, Angelic , Celerity and whatever else I could throw at it , those periphery happened so fast for whirling blades that Proc out since chakram returns so quickly at higher attack speed and attacks so fast too.