Gasoline can make some pretty impressive booms if you do it right, but I won’t give the details here. You are correct about speed making the difference; high explosives don’t release much energy but they release it all nearly instantaneously.
It certainly makes some pretty impressive noise when it explodes in the cylinders of a Harley.
I'm guessing that being compressed to a few hundred psi before being ignited has something to do with it.