I have an 06 and replaced the battery last year and put a CTEK charger on this winter. I really don't expect to get more than 3 years out of a battery and would rather change them out at the first sign of trouble after that period. It's not worth it to prolong buying a battery, they are not huge $$.

 

Get the porsche charger / maintainer that plugs into the cigarette lighter. You will love it.

 

Indeed it turned out to be a dying battery. I put it on the charger for a good 40 mins at least, while my buddy and I went for lunch. We came back, and the charger's display was lighting the green LED on and off in a cycle while the voltage needle was swinging from 0 to max back and forth. Never saw this before and we figured it's just a battery dying to be put out of its misery.

I went and got me a new one (see link above) and voila, she now cranks MUCH better, as intended. I've never had the starter crank up this good, ever, since I've had the car.

Finally, she will never sound slightly embarrassing when fired up !

 

Guys, I wish our Carreras had starter motors that sounded like this!

http://www.youtube.com/watch?v=C5nIXD63dM4

There's something about the frequency, whirring so quickly, that makes it sound oh so nice. Maybe it's just me ... but I wish all high-end sports cars to have it like Lambo

 

All fixed.. we replaced his battery today... No more slow cranking...

 

Next step: Mod it to crank like that Gallardo please !

 

That certainly could be it. It will be an interesting experiment - aided by topping off the battery with a charger just to know that you are starting from a known and high-powered level. OTOH, it might be too late. That is, the battery may no longer be able to hold a charge.
But either way, keeping low amperage devices that have no on/off switch (or have a switch but you may forget to use it) connected will end up causing problems.