[1] http://arstechnica.com/apple/reviews/2011/07/mac-os-x-10-7.a...
Not hibernating properly, maybe (still: why hybernating? Isn't "sleep" the default OS X thing and proper mode to use?)
Generally slow, I haven't felt at all. And it's hard to measure with just your "feeling" of "slowness". There are also tons of factors to contribute: use of new apps, a more fragmented disk (if upgrading instead of installing fresh), etc. Can you run a benchmark on the two versions and compare them?
https://discussions.apple.com/thread/3194235Non sarcastic version: Apple's way is that of changing things and deprecating stuff.
Assuming you don't depend on a app that only works with a previous version, you have to have the latest version of the OS, or you get left behind.
There can be a slight annoyance to move things forward and adjust to some changes that each new OS brings, but you get improved cohesion with the whole Apple ecosystem, new features and APIs, usually performance improvements, and (most of the time) architectural improvements to the whole OS/userland/API stack.
The advantage is you don't get tied down by backwards compatibility. The disadvantage is that things can break between major releases --but never for too long.
MS Windows way is of maximizing backwards compatibility. You can still run programs made in, say, 1995 just fine. The benefit of this is less hassle in the "will it break" department. The problem is bloat and inconsistencies, because MS adds each new framework/feature not as a pervasive change but as an orthogonal addition. So, for example, they change the file dialog UI in Windows Vista, but tons of apps still display Windows 98 era file dialogs or worse. Or they have 3-4 different APIs for the same thing, and they support all of them, diverting resources from making the OS leaner and future proof.
If I was a business (corporate) I'd probably like the MS way more, as it's more dependable.
Regarding where I want computing to go, though, I like Apple's way more -- I can live (and work) with a little pain every couple of years better than we seeing things go unchanged for a decade or more despite better options being already available.