How to avoid 100% CPU load when screen-sharing through zoom...
Zoom's screen sharing often causes high CPU load, which can slow down other applications, and on laptops the CPU fan might run at full speed.
To fix that, open Zoom's settings dialog (cog icon in the top right), and in the "General" section set the "Limit your screen share to X frames per second" option.
You could try a low number, like 5 FPS, which seem slow but is often adequate for simple demos and other sharing.
To reduce CPU load more, try disabling the video while sharing your screen.