Fonts on my iMac randomly become blurry (badly anti-aliased) until restart I have a late-2009 iMac with Yosemite 10.10.2.

Recently, I've noticed that some system fonts randomly become blurry, as though there's a problem with the anti-aliasing. This affects:


The OS X Menu bar
The right-click context menu
The side-bar in the Finder window
Etc.


In this screenshot - you can see how the text in my browser window looks sharp, but the right-click context menu items are blurry:



They are not blurry when I restart. At some point, usually with in a few hours, and not after any specific, repeatable event - they become blurry. (I've never noticed exactly when it happens. All of a sudden, when I stop focusing on my work, I notice that they're blurry.

If I restart the Mac, they become sharp again, but only temporarily.

I've never played around with any settings that might have caused this change (e.g, I haven't changed LCD font smoothing or anything). And I haven't replaced the graphics card. In short - I haven't changed anything that I'm aware of.

Thanks in advance for any advice or insight!
Perhaps you should change your font smoothing strength  and contrast settings. Many other people are having the same problem. Check out this link for information on how to do this