Loading time: Adsense ads codes from 2009, 2010 vs late 2011 and 2012

[Zivush]

Has anyone noticed load time differences between ads that were created 2009 0r 2010 versus ads that were created in late 2011 or 2012?
Ads are a big headache when it comes to improving site speed - My biggest setbacks are the AdSense ads.

I have seen an old post in Google code blog where they announced an improvement of ads speed: [googlecode.blogspot.co.il ]
They also mentioned that - web site owners don’t need to do anything to get this speed-up (it’s automated).
However, before testing, I suspect the old ads are still running slower.
Any inputs are appreciated.

[levo]

The improvement is that the code creates an iframe instead of blocking the browser while loading the necessary files. There shouldn't be a difference for new/old ads.