My macbook pro runs slow, iTunes videos keep stuttering. Nothing has worked to solve this issue. Macbook Pro 13-inch mid 2012 2.5GHz i5 with 8GB RAM upgrade.

Question

Hello everyone.
I have been having this issue for a few months now and nothing works to resolve it. The biggest issue is that iTunes videos constantly stutter ever few seconds, the audio portion of the video is not effected. The most I have open at once is Safari, Skype, and iTunes, and possibly Open Office. Videos will even stutter with nothing else open other than iTunes. At times it sounds like the computer is running something in the background from hard drive noise.
I even upgraded the RAM to 8GB and it still has this problem! Nothing looks wrong in Activity Monitor other than occasionally the memory usage spikes up to 6GB, but even then the memory pressure graph is green. I dont understand how these non-intensive programs can use that much. The hard drive is barely 1/3 full.
Please help with a solution as nothing has worked so far. Thanks!
Macbook pro 13-inch mid 2012
2.5GHz dual core i5
8GB DDR3 RAM
500GB HDD
Intel HD graphics 4000

Answer 1

Please read this whole message before doing anything.
This procedure is a diagnostic test. It won’t solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
The purpose of this test is to determine whether the problem is localized to your user account. Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”
While logged in as Guest, you won’t have access to any of your documents or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this behavior; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.
Test while logged in as Guest. Same problem?
After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.
*Note: If you’ve activated “Find My Mac” or FileVault in OS X 10.7 or later, then you can’t enable the Guest account. The "Guest User" login created by "Find My Mac" is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.