You can usually find them on the manufacturer of your device ('Dell') or the specific component ('Nvidia'). I recommend checking that your graphics drivers are up to date, as well as your OS (Windows, macOS, Android, iOS). You're also going to see more power drain from other components like the screen (stays on, lit up) and network adapters (Wi-Fi's constantly going, sending and receiving data throughout the meeting). Most devices these days have specialized hardware to handle H.264 decoding, referred to often as 'hardware transcoding' or 'hardware acceleration' and is a feature of either the CPU (processor) or GPU (graphics card/chip). For most scenarios that's not too terrible on processing power as the streams are all H.264 SVC.

Screen-sharing, and each webcam thumbnail or video you see on the screen is a separate stream that your computer is receiving, and Webex has to do some transcoding to fix thumbnails and the like to the specific resolution of your screen. Webex also has to use some processing power to decode and render multiple video streams. If you switch off your webcam video, you should see CPU usage go down a bit. If you have your webcam turned on and sending video, your computer has to transcode that webcam video to the different resolutions requested by different participants in your meeting. That's kind of tricky to nail down, unfortunately.

Cisco webex mac share screen