Windows 7 to break previous API compatibility
thebetaguy.com
thebetaguy.com
I can't imagine that the number of libraries is what's slowing Vista down... rather, it's just what those libraries are actually doing.
The other possibility is all of the memory mapping of hundreds of little libraries into the system plays havoc with code locality and L1, L2 caches in microprocessors. Since Vista is trying to be "more secure", there are probably more monitors and validation between these address spaces than there were before.
Now with Vista on just "what the libraries are doing", maybe they just turned a bunch of interns loose on a bunch of API's embedded in those libraries and they did the "almost simplest thing" that could possibly work without thought to performance. "Get it working and ship! Optimize it later."
I find Vista a nuisance to users who complain that nothing looks the same and the "trivial" modifications of user-interface derail the "learned-by-rote" user.
Microsoft would do the world a gigantic favor if they just conceded and made the world "Microsoft Linux." Apple did the right thing already with adopting a "UNIX" core to base their systems and and put all the money into UI and feature improvements. Microsoft is spending too much time overworking their engineers who work on continual bomb squad responses to exploding deck chairs to focus on usability for users.
On the other hand, if they're simply talking about a conventional compatibility box, this is less of a worry -- Windows has been doing variations of this for years for backwards compatibility -- since long before OS X.
This article skips past all the technical details, but the smartest solution might be to make the new API purely managed (i.e. .Net), and run all unmanaged apps in a compatibility box. This is great for stability, and it ends the days where you have to dig down into C or C++ and mess around with window handles to use certain OS features that aren't available otherwise.
Given MS's history of not giving high priority to reliability and quality, it's typically a good predictor of the future