When playing live, songs are usually much faster than the album version, particularly for rock and metal. When you listen back to early demo versions of those same songs, they’re usually a fair bit faster than the final recording, too. So at some point along the way, someone decides “ok, we’re setting the tempo at X BPM when we record this for real”, which is - apparently - not the tempo that came naturally to the musicians originally, or afterwards when touring the album.

How do they decide? Is there a rule of thumb producers are working with when it comes to the speed of a recording?

Cheers!