For example, the essential difference between a co-founder and employee #1, and why you might want the one to perform some set of duties rather than the other.
But assuming you can afford employee #1 (making cost somewhat moot), why otherwise might you decide to go in either direction?
I haven't employed anyone, but I'd say if the only thing you need is to 'speed up' as OP says, employing someone is probably the way to go. If you're still feeling your way around finding traction then maybe a cofounder. But this is just my 2c.
I just wanted to see further discussion of co-founder vs. employee (#1). I tried to ask it in an enthusiastic way.
This is why I'm single, I guess. :)