Copying to your external drive is painfully slow: the six usual causes

Finder says two hours for a folder you expected to copy in minutes. Slow copies almost always come down to one of six things, and most of them can be checked in a few seconds.

1. The connection is running at USB 2 speed

Open System Information and look under USB. Select the drive and check Speed. Up to 480 Mb/s means USB 2, which tops out around 35 to 40 MB per second, no matter how fast the drive is.

The cause is usually an old cable, a USB-A adapter, or a cheap hub. Plug directly into the Mac with the cable that came with the drive.

2. Thousands of small files

Copying 100,000 small files is far slower than one file of the same total size, because each file has its own overhead. Developer folders and photo libraries are the classic case.

# How many files are you copying?
find ~/path/to/folder -type f | wc -l

Zip the folder first, or leave out folders that rebuild, such as node_modules. See compressing files.

3. A hard drive, not an SSD

A portable hard drive reaches around 100 to 150 MB per second with large files, and much less with small ones. That is normal for the drive. External SSD or hard drive compares them.

4. The drive is nearly full

Drives slow down as they fill, SSDs especially. Keep some space free.

5. Spotlight and antivirus scanning as you copy

Spotlight indexes a new drive as files arrive. Add the drive to System Settings, Spotlight, Search Privacy if you do not need to search it.

6. Finder itself

For very large copies, Terminal can be faster and can resume if interrupted:

rsync -ah --progress ~/path/to/folder /Volumes/YourDrive/

If copies fail rather than crawl, see Finder error codes.