Same issues, using MacBook Air 2017. Updating to the Big Sur slowed down the booting speed 2X or 3X.
Photo Booth Camera doesn't work
Ram consumption has peaked up and is lagging the whole system for no reason
Even the smallest of task is lagging, which never happened in the previous Mac versions
Can't login to FaceTime and Messages app
Due to the lag, even typing on keyboard is lagging
The widgets might be the reason the whole system lags. (I don't want those feature then)
System - MacBooks Air 2017 (i5, 8GB RAM, 128 GB)
geekykant
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