Re: "Zoom degrades overall machine performance when actively being used"
Using Zoom requires a strong wi-fi connection and signal.
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Re: "my laptop appears to get slow and lag in places. It’s also getting hot and I can hear the fans coming on".
Check your computer has plenty of memory / storage free for the computer to operate smoothly.
(Eg: Good to have at least 50Gb free, at all times, in which the computer can operate.)
Ensure good ventilation, and check that nothing covers microphone, speakers, openings in the computer.
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Re:" I’m concerned about the performance of the computer when I have to take Zoom meetings with more than one person".
If it is possible for your set-up / provider hardware.
You may want to try using an ethernet cable between modem and computer for important Zoom sessions.
(You would likely need to use a suitable adapter between the ethernet cable and your MacBook Air port.)
(The main drawback is the computer is less portable during the Zoom session.)
All the best :-)