We have identified the bottleneck in the Flash Player for OSX. Like in the other plugins the culprit is text rendering, in this case rendering using device text. This benchmark spends >50% in a single OSX function: ATSUGetUnjustifiedBounds. You can verify this yourself using Shark. I am working on a change which will cache the results returned by that API to where this call should completely disappear from the performance profile.
If everything turns out well I hope to see that change in future release. Some new numbers on my Mac Pro (note that these represent numbers which can change at any time if we decide to do things differently):
Before the change: ~8.5fps
After the change: ~28fps in Safari (~26fps in Firefox)
This speaks volumes about how little platform specific TLC Adobe historically put into the Mac plugin. A performance bottleneck as glaringly obvious as this should never have been seen by a user, much less bedeviled users and Flash developers for years before someone bothered to run Shark, or now days the CPU Sampler Instrument. Adobe must never have tried to optimize on the Mac at all; if I found a common use case where I was spending half my time measuring the same block of text over and over again, I'd joyously jump on the opportunity to make my user's lives easier because I could fix that in an hour. Apparently, Adobe couldn't be bothered to do the right thing until years later, and countless hours were lost by Flash developers trying to coax the Plugin into looking just as smooth on the Mac as it did on Windows.
And now that Apple is the big dog in the mobile application space, it's payback time for all the years of neglect and shoddiness. And with the eyes of the world upon it, Adobe is having to do the actual heavy lifting of getting decent performance and battery life out of a handful of Android phones just to prove Apple wrong. At least something good might come of this.
In the meantime, I've installed Click to Flash on my Mac and gotten iPad like silky smooth performance out of Safari. it is amazing what all those little ads cluttering up the dozens of open pages I tend to accumulate were doing to my poor MacBook.
