Deathmatch Goku VS Superman

Namek is not larger than Earth. Even assuming it was twice the sizeof Earth, that's still sub-light speed. Light circles Earth at the equator 8 times per second. We can clearly see that Goku didn't cross the entire planet anyways, but let's assume he did.

Light would go around a planet twice the circumference of Earth 4 times a second, and that's complete revolutions (going from the starting point back to the starting point). It would do what Goku supposedly did 8 times a second, while it takes Goku a full second to do this. Goku, at base, in that scene, is less than half light speed assuming Namek was larger.

Of course, that's assuming Namek was larger. If we assume it was larger, due to the heavy emphasis on gravity in the series, the increased mass should've made it impossible for Bulma, and would've been a plot point for the characters. This implies that Namek has the same gravity as Earth.

from here, we know that if it had a larger radius that Earth, it would also be much less dense and more unstable. Essentially, it would be far easier to destroy than Earth. This would point to most DBZ characters not being as destructive as they claim, something I'm very opposed to. Frieza should be more than capable of destroying either world!

The only reasonable thing to do is to assume that Namek is the same size as Earth, thus having the same gravity and density. Unless there's something that says otherwise, this is also the default course of action.