Mike Hill has a lovely little essay titled "How TDD and Pairing Increase Production."

If you want more production, look first to raising your internal quality.

...

Do I really still need to rehearse this? All day long, every time you make a move, you will be depending on the code that?s already there. Every line of it you have to study will slow you down. Every extra open dependency will slow you down. Every bad variable name will slow you down. Every flawed design decision, be it big or small, will slow you down.

If you want to work as fast as you can, you want to work with clean code. Period.

There's a lot of truth in that essay. Go read it.