Make sure that you optimize the background images or motion videos to the display resolution. You want the resolution of the video or graphic to be the same as the display. If you use an image that's 8,000 x 3,000 resolution and are only displaying on a 1024 x 768 screen the system has to work harder to downscale the image to the lower resolution. It's even worse with video/motion backgrounds and with an older computer, especially one with a spinning rust hard drive. Using a resolution SLIGHTLY higher shouldn't cause a problem (say 1200 x 1000 image on 1024 x 768 screen). It's mainly when the image/video is considerably larger.
Knowing your hardware specs of the computer, what version Windows you are using, and what resolution your FOH display is would help us with this.
Also have you checked your hard drive lately? Does it have at least 10% free space (20% or more is preferred)? Have you run a chkdsk on it to rule out any drive errors? Is the drive starting to fail? I would start there, especially if it's more than a couple of years old or a laptop.
Check Drive Health. This does not need to be installed. Just extract the Zip file and run the program from there.
https://osdn.net/projects/crystaldiskin ... 8_1_0.zip/
How to run Checkdisk in Windows
https://www.howtogeek.com/howto/windows ... ows-vista/