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No problem here

At this very moment I have 3 GB occupied by pRon alone.

And climbing. Darn you Oron.
 
Turn off Photostream in iPhoto worked for me!

Turning off PhotoStream in iPhoto seems to have worked for me!
 
To Seared

Solution

Should you be running out of storage, you will keep seeing alerts with a link to your storage preferences where you can manage your storage. To access this section without this direct link, follow these steps:

  1. Click on the Apple logo in the top left of your screen and choose About This Mac.
  2. Next, click the Storage tab. This will show you how much storage you have available and how it's used. You'll see a bar which indicates how much space is given to Photos, System, Apps, Mail, and so on. This has changed slightly in later versions of macOS because now so much content can be stored in iCloud.
    Here's how this looked for us back when we were running Sierra. Back then we have more than 92GB of photos on our 121GB drive, and 738MB of purgeable stuff.
  3. when you get the pop up message of disk space low, its related to the current action you were working on. you may have dump or downloaded or synced iCloud or something. Just look at the list of large files and move or delete them from the HD if you have space on an external.
 
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