The roadmap for Adobe apps becoming 64-bit-native is a bit complicated, with some (Lightroom on Mac & Windows, Photoshop on Windows) being there now, some (Premiere Pro, After Effects) largely there now, and some yet to come. To provide an overview & to outline some performance benefits, the company has created a white paper (PDF) on the subject. [Via Anita Engelman]
Update: In response to a question in the comments, After Effects PM Michael Coleman has added some more details:
Jerry raises a good question: Can a 32-bit app be architected to take advantage of 64-bit OS?
Prior to multi-core rendering, all rendering took place within the bounds of a 32-bit memory space. Today, parallel processing is the key. If After Effects weren’t architected to take advantage of 64-bit, all your processor cores would be using the same small chunk of RAM. Instead, multi-core rendering on a 64-bit OS can use up to 4GB per core. After Effects has been rendering faster because of this architecture since CS3 shipped back in 2007. And it’s been improved in CS4.
What about optimizations? Let’s say you only have 2GB of RAM. You might assume that you’re not a candidate for some of the improvements offered by using CS4 with a 64-bit OS. But this isn’t the case. After Effects uses RAM intensively, and it can do so more efficiently and reliably on a 64-bit OS.
In some respects, After Effects is a hybrid – a little bit like a Toyota Prius. Is it practical to be completely electric? Not yet. Does that mean that we should give up spectacular gas mileage and clean-burning technology now? No way. These are great advances and you don’t have to wait around for the Chevy Volt. Like CS4, the Prius is improving the world now. You’ll have to wait until 2010 for that Volt.
All things considered, CS4 and a 64-bit OS are probably one of the best investments you can make in 2009.