Welcome to the Apple Support Communities
First of all, make sure that you need Flash. Most of the websites now supports HTML5, so you don't have to install Flash. If you need Flash, you can install it without problem.
Generally, Flash causes problems on Macs (principally, overheating and sometimes, kernel panics), so you can install the ClickToFlash extension on the Safari Extensions Store (you can access to it on Safari menu) to use Flash only when you need it
not as a whole
but running flash in form of videos and games and the likes take a toll
in terms of performance while it's being don
mostly because of the poor implementation of the plugin
same reason why adobe never made a flahs player for ios
and why they pulled the android player a while back
flash is on the way out even adobe say this but it may be here for a while yet
but just having it installed will not slow your computer down
mende1 wrote: Most of the websites now supports HTML5, so you don't have to install Flash.
I'm not seeing this (running Firefox 17.0.1, maybe not supported) and I'm reading in various places that HTML5 is not really ready for prime time. Do I need to install a separate HTML5 player?
Can you perhaps give me a link to a site where I can try out HTML5. I'd like to learn more about it.
I think you missed the new versions recently. They now use hardware acceleration and the gpu.
As far as performance and battery consumption all tests done on the two technologies html/flash show Flash being WAY ahead.
The only time html5 video is better is if it uses h.264, is not played through the browser but instead downloaded to your machine and ran locally.
But Flash also plays h.264 video, and you can also download it with tools like realplayer and run it locally as well.
So that's a tie.
But more to the point of in the browser video watching, ever since version 10.1 flash pwns html5 video tag. Because no browser maker has yet to allow it acces to the gpu.
It's because Flash now uses hardware acceleration, and has access to the gpu.
2 years ago, Flash would have eaten up the cpu the same way. But since version 10.1 and Adobe's addition of "StageVideo" and "Stage3D" it runs like butter, using the GPU to render video and 2D/3D graphics while the cpu handles user interface overlays.
If you right click a flash object and click settings you'll see the new check box for enabling hardware acceleration. It's checked by default, but not every piece of flash on the web has been updated to use it yet, but most the popular sites have done so.
Here is a great list of Flash games that use the gpu.
You see that Flash runs on ios in app form but Apple won't allow the player to run in the browser.