I have to disagree with this.

Agile is a great way to manage the project management for a startup but a dreadful way to manage the software development. Pair programming doubles cost with questionable and unproven gain in productivity (definitely not 2x). TDD is a nice idea in theory but you double development time with questionable ROI. Also startups need to be continuously evaluating and improving user experience. This doesn't happen so well with TDD.

If startups are developing at the same pace as large corporations (or slower) then they are conceding their biggest advantage. So I would leave the pair programming and TDD until you are no longer a startup.