Joe Fighter has a 2-handed sword. Bob Rogue has a dagger. Who gets to hit the other one first, everything else being equal? When speed factors are used, Bob Rogue does. In reality, Joe Fighter has a much longer weapon and would get in a blow before Bob Rogue could close.
Aside of that obvious fact, many people forget that in reality a sword wielded two-handed is faster than when wielded one-handed. While in D&D wielding it with two hands allows for extra strength, probably because they have no speed system.
If you don't understand what I mean, grab a stick and wield it trying to swing with it (make sure there are no people or objects near you first). Now try the same but instead hold it with your main hand and then use your off-hand on the weapon as if wielding a lever. In the end, wielding a weapon two-handed doesn't make you stronger, it makes you faster.
Of course this mostly applies to balanced swords, I have no experience wielding greataxes.