It might disable Flash hardware acceleration. (link)
Something to take into account if you are thinking of updating right now. You may want to hold off until the issue is resolved... or at least until the next test is over. ;)
How can they build flash into lion? Isn't that a security hole? I can't see apple ever choosing to update as frequently as adobe nor caring about security as much. Look at how they handle the Java updates.
@FairTradeFullStacks - It's been an issue with earlier versions of the Mac OS I've found, at least with Java based items.. They build a version of Java into the Mac OS as well and I've often found it lacks essential features and updates. Apple tries to keep close control over every essential piece of software on their machine, meaning that there is often a strong disconnect to original platform developers. It's one of my complaints AS a developer with Apple. Windows has it's own share of problems, but it and Linux are very friendly to developers. OS X IS a proprietary version of Unix. Closely connected to Linux, but it's also proprietary. Ever seen a zip file as done by a Mac? It adds extra files to the zip. One for every file and folder that's being zipped up and one more that says "I was zipped on a Mac" basically. It can often greatly expand the size of a zip file. I once uploaded a bbs package to a host that I had zipped up on a Mac. It took me weeks to figure out that all the broken features were due to those nice, hidden, extra files that the Mac had added. That was OS X 8-9 I believe. A buddy of mine who does contract work for Apple says it hasn't changed.
@FF - Java is decoupled from OSX now as well. In Lion, first time you do something that needs Java it offers to download it for you. Apple no longer maintain it themselves.
We don't recommend you upgrade to Lion given the Flash issues that Apple introduced by disabling hardware acceleration and breaking the ability to click anything in the Flash settings panel. Unfortunately, the game's performance suffers greatly, but I suppose that is further motivation for me to improve it :)
Update from the Adobe website (http://kb2.adobe.com/cps/905/cpsid_90508.html) :
Flash Player may cause higher CPU activity when playing a YouTube video. Possibly related to disabled hardware acceleration.
UPDATE: The final release of Mac OS X Lion (10.7) provides the same support for Flash hardware video acceleration as Mac OS X Snow Leopard (10.6). The previous “Known Issue” suggesting that video hardware acceleration was disabled in Lion was incorrect and based on tests with a pre-release version of Mac OS X Lion that related to only one particular Mac GPU configuration. We continue to work closely with Apple to provide Flash Player users with a high quality experience on Mac computers.
It's been fine throughout the Lion beta test, don't panic. As Wundur quoted above, it was an erroneous report from Adobe.
More at www.computerworld.com/s/art...
OKAY! If you *are* seeing bad Flash performance in Lion, try closing *all* other browser tabs when playing (yes, all of them). I think I figured out the problem, but it's an Apple/Adobe problem rather than one we can fix.
(I'm not seeing Flash instances in inactive browser tabs throttled to 2 FPS as they should be -- this would mean that all instances of Flash are running at full speed at all times.)