The bottom line is that when there is insufficient space on your startup disk for the swap file macOS must create, your Mac will slow to a crawl. After restarting, my swap file was reduced from 9GB to 0 bytes. After using my MacBook Pro (with 16GB of RAM) for two days without restarting, my swap file was 9GB after a restart it dropped to 0 bytes.

When you reboot your Mac, it resets itself to zero and grows dynamically from there as needed. This swap file grows and shrinks dynamically, but typically requires several gigabytes of disk space. If your Mac doesn’t have enough RAM to perform an operation, it creates a “swap file” on your startup disk, and then uses that swap file instead of the RAM it needs. If you’re wondering why a shortage of space on your startup disk affects your Mac’s performance so dramatically, it results from the way macOS’s Virtual Memory (VM) scheme works. If you save (or download) a few large files, your disk will be nearly full, and your Mac will slow to a crawl.Īnd, if your startup disk has less than 10% of its space available, it won’t be long before you encounter slowdowns and spinning beachballs because of insufficient available disk space. If your disk has less than 20% of its disk space available, you’re headed toward trouble. Used tells you how much disk space is in use.

Available tells you how much disk space is currently.Capacity tells you the size of your drive.These are the three salient items: Capacity, Available, and Used. You’re interested in three items near the bottom of the General section of the window: Capacity, Available, and Used. How Much Space is Left on my Disk?įirst, select your startup disk’s icon in the Finder and choose File–>Get Info (or use its keyboard shortcut, Command+I).Ī Get Info window with details about that disk will appear on the screen. So… let me offer you a quick lesson in disk space. Worse, many Mac users don’t even know where to look for that information on their Mac. In my experience, many (if not most) Mac users do not understand how close to capacity their startup disk is. And, you’ll notice that activities that used to happen almost instantly-such as launching apps, opening documents, or applying filters to photos - take much longer. Did you know that your Mac’s performance deteriorates significantly as your startup disk fills up? As your startup drive gets closer to being full, the spinning beachball will appear and slow you down.

How to clear room on startup disk mac