Change Your Monitor’s Display Resolution
A setting that you can change to potentially improve your Mac’s performance is the resolution of your monitor. Most modern monitors and video cards (or onboard video circuitry, depending on which Mac model you use) can display multiple degrees of screen resolution. You change your monitor’s display resolution in the Displays System Preferences pane.
First, click the Display tab and then click the Scaled button, which makes a list of resolutions appear. Select the resolution you want to try from the list below the Scaled button.
You see much more at native resolution, but everything is much bigger at lower resolutions.
Here’s the deal on display resolution: The first number is the number of pixels (color dots) that run horizontally, and the second number is the number of lines running vertically. It used to be that fewer pixels refreshed faster.
But with LCD and LED (flat-panel) monitors and notebooks, this usually isn’t true — or if it is true, it’s almost unnoticeable. Furthermore, because you can see more onscreen at higher resolutions, a higher resolution reduces the amount of scrolling that you have to do and lets you have more open windows on the screen.
Finally, the highest resolution is almost always the “native” resolution of that display, which means it will usually look the sharpest. So you could just as easily say that higher resolutions can speed up your Mac experience as well.
On the other hand, if you can’t discern icons in toolbars and other program components, using a lower resolution may actually enhance your work speed.
Choose a resolution based on what looks best and works best for you. That said, if your Mac seems slow at its current resolution, try a lower resolution, and see whether it feels faster.
Although you can use OS X at resolutions of less than 1024 x 768, at least with some models and monitors, Apple has designed the OS X windows and dialogs on the assumption that your resolution will be at least 1280 x 800.
So, if you choose a resolution lower than that, some interface elements in some windows or programs may be drawn partially (or completely) off-screen. Just keep that in mind if you choose a resolution less than 1280 x 800.