Viewing and scaling layout viewports
If you have created numerous layout viewports, your system performance may
be affected. If necessary, you can turn a layout viewport on or off. Turning
off a layout viewport does not delete the viewport or its contents; it simply
turns off its display.
You can also change how you view items within a layout viewport by specifying
a scale factor, which changes how large or small model space entities appear
within the layout viewport.
To turn layout viewports on or off