I recently installed Ubuntu 13.10 on a 2011 late Macbook pro. With the same version chrome and pepper flash plugin and flashblock extension to block irrevalent flash. When I watch some flash video online, I found that CPU usage is much higher under OS X Mavericks than on Ubuntu. And the MBP gets hot and fan runs very quickly under OS X, while in Ubuntu it is very cool as normal when watching same flash video online. I find it unintuitive because OS X should have better drivers than linux on MBP, making it more power-efficient and usually cooler. What could be the reason?
Since you can't make any assumptions about how Flash for Mac or either Flash for Linux are implemented or how they utilize efficient APIs of their host OS you can't make any statements about why performance behaves so differently.
As long as graphics acceleration for video playback is available on both OS's it should be Flash's task to correctly use it. You might want to check if Hardware Acceleration is enabled in Flash on Mac OS. To do this, right-click into a Flash-Applet and select "Settings...". Then, in the first tab (Display), you should be offered a Check-Button labeled "Enable Hardware Acceleration".
Performance is also dependent on the video codec of the media file. HD content from youtube for example only takes 10% CPU-time for me, whereas Flash content from other websites may also get my fans started.
Four things come to mind immediately that would cause what you are seeing:
- The server is serving higher bitrate or a file that's encoded differently on OS X versus Linux.
- The flash player code itself is better optimized on Linux than on OS X.
- The code on Linux is calling better API than on OS X.
- Other tasks are taking CPU or adding load on OS X and not on Linux.
My guess is a combination of several would be in play.