My atv 2 quit sharing or became extremely slow (spinning circle)

Question

Recently (since software upgrades to itunes 11 and apple tv) I am now unable to get past the spinning wheel when tryig to watch shared movies or listen to shared music(though music now seems to be working) from the iMac.  I upgraded my cisco e2500 firmware and assured that multicasting was not filtered.  I can neither push a movie to the apple tv nor pull one from the apple tv menu, though the movies, etc do appear with their artwork icons and begin to try to stream.  I am able to watch Netflix movies and podcasts with no issues.  I have also rebuilt permissions on my hosting iMac.  The iMac is not asleep during these tests.  Movies play as normal on the iMac when I watch there, though when I click and select the apple tv as the output device it does not get past the spinning wheel on the TV.  OSX 10.8.2 installed.
I am  able to share from my iPhone or iPad to the atv (both video and music).
Any ideas what may be going on with my iMac?  Thanks in advance.

Answer 1

First thing to check is how full is your hard drive? Do you have at least 10% free for systems usage? If it's full, that will put a real crimp on performance.
Second, if you don't run any sort of disk maintenance software, I'd recommend OnyX available from http://www.titanium.free.fr/download.php .  Run the tasks on the cleaning and maintenance tabs, which may require reboots. Good practice suggests you should have a backup before running any disk maintenance software. Many have found that using OnyX periodically makes a difference in performance.
Next, bring up the Activity Monitor, and on the system memory tab, look at page ins and page outs. If page outs is greater than 10% to 15% of page ins, you need more memory for the programs you run. A page out happens when memory is full, and the system needs to write a memory page to the hard drive to make room for something else. Too much of this can slow the system down. I know you said the system is slow with nothing running, but look at this.
In system preferences, look at your login items to see if anything is being loaded into memory that you don't recognize. If you want to test this, create a new user ID with no options of any sort, so when you log in you're as bare as can be. If that makes a performance difference, then look at your login items.
You can always run the Apple hardware test if you want to ensure the hardware is working properly. And while you have your original OS X disk out, run disk utility and repair your hard drive. If it has any errors and can't complete, post back here for next steps.
And, for your reading pleasure, if you haven't already, this has some good information: http://www.thexlab.com/faqs/performance.html