The performance of an Office program (other than startup and shutdown) is reduced.
If you see bright or dark spots on a flat-panel or Mac notebook computer screen: Your display may have pixel anomalies. Try relocating nearby electrical devices or moving your Mac and display. You may also be experiencing interference from a nearby power line, a fluorescent light, a radio, a microwave oven, another computer or another electrical device. If the display is flickering: Make sure your Mac and display are connected to one another with good quality cables and adapters. Then click the button to detect the display. To see the Detect Displays button, press the Option key. Choose Apple menu > System Preferences, then click Displays. If your display is blurry: Make sure your Mac has detected that display. If that doesn’t work, try calibrating the display. For example, if you’re using a Thunderbolt display, choose Apple menu > System Preferences, click Displays, then select Thunderbolt Display in the Colour Profile list. If the colours don’t look right: Try using the display profile designed for your display. If images are too large or too small: Try adjusting your display’s resolution. If the display is black or dim: Try adjusting your display’s brightness.
Install and reinstall apps from the App Store.