I'm so nervous to update my iMac. I've heard stories of updates not playing nicely with Photoshop and my computer is pretty old too, so I am worried it will run slower with a new OS. Right now it handles Photoshop CC and Final Cut Pro pretty well (though I do have the weird black boxes showing up in PS sometimes).
I have a mid-2011 27" iMac with 12GB of ram. I have 10.10.5 installed on it right now, and I try to keep it clean with CleanMyMac. Should I try updating to Sierra? Aside from making sure Time Machine is up to date, anything else I should do beforehand?