How do I optimise system storage on my Mac running macOS Monterey?

I had the this problem but I've found a solution that worked for me at least. Im running macOS Monterey.

I tried replying to old threads with this issue but apparently I can't. So I'm creating a new thread.

My Macbook's system data size had ballooned to nearly 150gb in 250gb internal drive, basically occupying whatever space was available on the internal drive and it was down to 1gb available. I was keep getting the notification of no storage available. I looked into all the folders and everything seemed in order including Cache folder which showed only 5gb data in it, so I ignored it thinking 5gb is not gonna make much difference.

But after struggling for a few hours I decided to inspect everything in detail and here's what I found.

I clicked Go button in the menu then Home from the drop-down menu. Used short key "Command+Shift+ . (period) to show hidden folders. I switched to List-View with file sizes to see folder sizes. Then Library > Caches > CloudKit > Com.Apple.Knowledge-Agent > then the biggest folder in it with a long alpha-numeric name > then MMCS. Now in that MMCS folder there were 4 files with names like "tmpm-0x000000000000001b".

These 4 files' size combined would add up to only 4gb in List-View but once I right-clicked and got into "Get Info" they were actually around 100gbs. I deleted all these 4 files, restarted my macbook and now I had more than 100gb storage available and system data size was somewhat back to normal, although, it's still occupying 40gb but at least its better than 150gb.

I don't know if it's gonna work for everybody but at least its worth a shot. It might solve the problem for some people, I hope.

Thank you BDAqua for the information, I didn't know about this shortcut. Makes it much easier if it works.

But what if the Terminal doesn't show the actual sizes (around 100gb) and only shows the sizes that were shown in the list view (4gb)?

Cheers