What would happen if the rate of seafloor spreading was faster than the rate of subduction?

If the rate of seafloor spreading was faster than the rate of subduction than we would have had much more land mass on the surface on the Earth. This will cause lots of very long and very high mountain ranges in the oceans (much bigger ones that the ones that are forming now) and because of the huge amount of magma that will be pushing through they will be getting above the ocean waters and forming new land masses, and that will make the world much different from what we now it now.

a. european colonies