& to make the thread drift a bit, Purple of the big 3, ( Sabs,Zep & Purple were in my view the biggest & most significant progenitors of heavy rock-metal of the 70's), were alone in playing REALLY fast stuff. Fireball & Burn to be exact.
They weren't a metal band, but did have elements of it in them. That was one of em. Sabs played mostly slow. Fastest track perhaps was Never Say Die. Which was nowhere near as fast as the aforementioned Purple tracks. Zep played Communication Breakdown, but no other fast stuff.
Rats in the Cellar by Aerosmith was pretty fast, & Queens Stone Cold Crazy kinda fast, but these came out 74-75, well behind the Purps.