Start with a clean install of Yosemite:
Its often easier to start with a “clean slate” then to figure out how to turn off and undo things we may have unknowingly turned on.
You did remember to back up your data and boot drives, right?
When you do a clean install you’re going to erase everything so now’s a good time to make and test (yes, test) your system backups.
Warning! With your clean install do not activate any automated features. Activate only one web browser, preferably Safari. Don’t activate any optional features or plug-ins such as Google Chrome. Chrome and Yosemite don’t play nice together anyway.
Now that you’re back to clean, and nothing optional has been added, I’ll show you how to turn off a series of default resident processes that automatically boot up with Yosemite.