It’s more about the early 80s LA music scene being influenced by the fast paced hardcore/punk sound of the time, they were listening to a lot of punk stuff and cranking the tempo / energy, with some metal infusion, hence songs like Reckless, Shadow, Nice Boys etc.
fast Crazy obviously had a slightly different emergence as it began as them jamming around The Seeker by The Who, then creating their own song from that on acoustic (slow Crazy) then turbo-ing it into fast Crazy because of aforementioned punk / metal influences.