Does an external monitor create a performance hit?

[jfreed]

I have a 2009 iMac and one of the first Cinema Displays. (I think it's about 2008 or so.). I'm wondering what kind of performance hit there is? Is it marginal or does it consume lots of resources? I'm running beta 1 of El Cap, if that makes a difference. Thanks!

 

[ixxx69]

I have a 2009 iMac and one of the first Cinema Displays. (I think it's about 2008 or so.). I'm wondering what kind of performance hit there is? Is it marginal or does it consume lots of resources? I'm running beta 1 of El Cap, if that makes a difference. Thanks!

Practically speaking, there's no perceivable performance hit for typical usage.

If you're running software on one screen that is highly GPU intensive, like playing a video game or GPU rendering, then there might be a slow down on the other screen.

Of course you can test this out and disconnect the external screen and decide for yourself whether you notice a difference.