Yes, objectively spoken it IS very slow, if you compare it to a boost cycle of 2 (!) seconds for 530 ms on my Krait 2 (585 in my Phantom) with just 1 pip in engines. And by the way, my Chieftain boosts every 3 seconds according to coriolis.... And that is with charge enhanced, super conduits on ALL of them."The chieftain can not do that, its boost cycle feels painfully slow in comparison." - why you say that, a Chieffy build with engine focus in PD can boost non-stop with 3 pips only...I never felt Cheffy boost "painfully slow" - a boost each 5-6 sec is "slow", in your opinion ? ...with a speed around 520-530 ?....
But hey, maybe you talk about PvP here.... and that is out of my consideration or arguments.
So there is no valid argument to be made for using ENG focused at all, especially considering its drawbacks regarding the other just as important capacitors.