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Hi @Anonymous ,

>>>>>>will autocad run smoothly on macbook air m1 2020 under rosetta 2?

Yes, AutoCAD 2020, 2021 and 2022 for Mac run smoothly on Macs with M1 chip under Rosetta 2 mode

>>>>>how long it took to render on macbook air m1 2020 under rosetta 2(just estimation)

If I understand your question correctly - AutoCAD for Mac doesn't include Rendering engine, you can use Autodesk online Rendering instead.