What could possibly be the reason of slowing down: suddenly processing became slower ex. saving file, renaming file, opening file.
Did you already check, if there still is enough free space left on your internal drive?
Free up storage space on Mac - Apple Support
Are you using iCloud Photos and your Mac is syncing data to iCloud?
Or using iCloud Drive to open and save your documents in iCloud?
Add your Desktop and Documents files to iCloud Drive - Apple Support
Your System Data seems to take up more space than usual, resulting in not enough free space to work correctly.
Have a look at this discussion, to find data, that is stored in this section and see if you can reduce this part by deleting files you don't need anymore. Before you start, make sure to have a backup.
macOS and system data - Apple Community
How do I delete files from System Data - Apple Community
If you are using iCloud Photos, archive the photos from iCloud on an external drive, so that you can reduce the size of your Photos App by deleting them, which will also delete them from iCloud.
Archive or make copies of the information you store in iCloud - Apple Support
In case you are not using iCloud Photos, copy photos you don't need to an external drive and delete them afterwards from your MacBook Air.
Thank you for the response. Yes Im using icloud. I am just wondering, with the space occupied by System Data, when my checked my friend it below 60G but mine is around 140G, dunno if its a factor? Thank you for the links shared earlier. Godbless
[Edited by Moderator]
I am using Macbook Air M1
