How to Fix Drive Transfering Speed is So Low

General
1

Hi there! I recently purchased two SanDisk Ultra SDXC cards to use as secondary storage, thinking they’d be a simpler solution compared to an external hard drive.
With specs boasting 150 MB/s, I expected these cards to perform impressively fast.

However, I’m only seeing transfer speeds of around 20 MB/s, as confirmed by both the Activity Monitor and the Blackmagic Disk Speed Test. When encryption is enabled, speeds drop further to around 15-16 MB/s. This is slower than my 12-year-old USB hard drive! What Can I Do?

2

Hello, here I list some suggestions, hope they can help you a lot.

  1. Check your card reader compatibility.
  2. Verify the write speed of your cards, you just listed the read speed.
  3. Test them on another device.
  4. Disable encryption(if possible.)
  5. Update macOS and drivers.
  6. Reach out to SanDisk support.

Good luck to you. :smiley:

3

Sometime, the storage space on your Mac or your cards will lead to transferring speeds lagging.
For more space, you can clear out unnecessary cookies or caches on your Mac and cards.
To optimize more storage, iBoysoft DiskGeeker for Mac is an excellent tool, which can scan and clean files as quickly as possible.

4

Please read: Slow External SSD and HDD on macOS.