[Theory] Why is MPLS faster than IPv4?

Good morning,

As the title suggest, why is MPLS faster than IPv4?

Correct me here if there's something wrong: a router has its own routing table, and consults it every time it needs to forward a packet. Now, if instead of the packet the router consults the label, what's the difference? It still needs a "label table", doesn't it?

Don't really catch why one if faster than the other.

Thanks to anyone who explains me the reason.

David