I just updated it. After update the system to Big Sur, my mac began to slown down. I changed to undo the system but didn't work.
MacBook Air(13.3', Early 2015)
1,6 GHz Intel Core i5
8 GB 1600 MHz LPDDR3
Intel Graphics 6000 1536 MB
MacBook Air(13.3', Early 2015)
1,6 GHz Intel Core i5
8 GB 1600 MHz LPDDR3
Intel Graphics 6000 1536 MB