Why Is My Flash Drive So Slow on Mac?

Why Is My Flash Drive So Slow on Mac

Any USB flash drive can work on a Mac computer as long as it has been formatted to Apple File Systems [APFS]. However, flash drive file transfer rates vary among different brands, models, and USB versions. But why does this happen? Why is my flash drive so slow on Mac?

Your flash drive is so slow on Mac because you’re using a 2.0 flash drive. Even when using a 3.0 port, the speeds remain slow because of a 2.0 flash drive. Another reason can be whether you format the drive through the Apple File System or not.

Though, that’s not all. There are other common issues that need addressing too. We’ll go through all that information in this article along with ways to fix a slow flash drive on Mac.

Key Takeaways:

  • Old flash drives tend to work slower on MacBooks. Even on 3.0 ports, 2.0 flash drives remain slow.
  • Flash drives transfer files slowly when they are of low quality and have large files to transfer.
  • You can increase the transfer speed of flash drives by upgrading to an updated USB version.

Keep reading to learn why a flash drive can be so slow on MacBook. I’ll also discuss how to test the flash drive speed and ways to increase the speed.

Why Is My Flash Drive So Slow on Mac?

There are several reasons that could make a flash drive too slow on a Mac. If your flash drive is taking too much time to copy files from Mac, these could be the main causes.

Why Is My Flash Drive So Slow on Mac

Transferring Multiple Large Files

When you transfer multiple large files of more than 1-2GB, the cache will fill up, resulting in a decrease in speed. The cache is the data temporarily stored within the drive when you transfer files.

Besides, the flash drive controller can’t withstand the excess work, and you will notice the files going from Mbps to Kbps and forth.

Thermal Throttle

When transferring data, a lot of heat is generated. Therefore, using your flash drive for a long will heat up to a point when the controller has to offer a cooling mechanism. This is crucial in order to keep the drive within a safe operating temperature.

However, the controller has to reduce the data transfer in order to cool down. This process is called thermal throttle or thermal accelerator.

Low-Quality Flash Drive

Flash drive controllers must process a large amount of data during the transfer. Cheaper flash drives use low-quality components. And low-quality NAND chips and controllers need to read and write at a slower rate to avoid errors. So, instead of buying the lowest-price series, you should aim for a performance series.

A Slow Storage Format

It could be slow because of the way the USB is formatted. Crook vendors tend to format their drives making the storage format slow and forcing users to buy a new one at some point.

For example, flash drives with FAT32 and exFAT formats are generally slow. This tends to show when copying pretty large files.

Slow Hard Drive Speed

When copying a file from the hard drive to your flash drive, the speed of the hard drive may have a breakdown. This can happen if it isn’t able to withstand the speed of the flash drive. Therefore, slowing down access to the file.


No, a USB hub will not slow down the file transfer speed. However, a USB hub with several devices connected may lead to a slower speed.

Overall, slow speeds are experienced when using a USB hub with multiple flash drives at a time. You can try to use a motherboard with multiple 3.0 USB hubs instead.

Read More: How to Go to the Root Directory in Mac?

How Do I Test My Flash Drive Speed On A Mac?

To test your flash drive speed on Mac, do the following:

  1. Start by connecting the flash drive you want to test. USB ports are usually found on the side or front of laptops, and on the front or back of desktop computers.
  2. Download the Blackmagic Disk Speed ​​Test application from the Mac App Store.
  3. Launch the application. The main window of the program is a dashboard with two speedometers. The left one is for writing speed, and the one on the right is for reading speed.
  4. Click on the settings icon located in the middle to select the USB flash drive or other drives whose read and write speed you want to test.
  5. Press the center key labeled Start to start testing.
  6. After testing, the results will be presented in the lower right corner of the screen. Therefore, take a look at the speedometers during the test.

How Can I Speed Up Slow USB on My Mac?

Slow flash drives are no fun. Who likes to wait 15 minutes for a 1 GB file to transfer, right? But there are ways you can improve the situation. Let’s find them out together.

How Can I Speed Up Slow USB on My Mac

Method 1: Upgrade to a USB 3.0 compatible adapter

Using a pen drive that is USB 2.0 can cause a slower transfer of data to a USB drive. Unless you upgrade or get the latest USB 3.0, the transfer rate will still be slower. Therefore, changing the Pen drive is the only method you can use to enable faster transfer of files.

Method 2: Disabling USB Flash Drive spotlight

The Spotlight tool present in the macOS is an indexing tool that creates indexes of all the files and folders. It enables you to search and find anything easily. The spotlight tool can cause a slow transfer rate, therefore turning it off can increase the speed.

Method 3: Converting FAT32 into APFS in the USB File System

A failure in the file system can be a reason for the slow transfer. You need to have the Apple File System instead of the HFS system. This puts focus on encryption, SSDs, and flash drives.

Your drive only works with Mac, hence the reason to format it to APFS. This is a crucial step when formatting drives to APFS. Overall, you’re trying to fix a slow flash drive by replacing the HFS version that might not run on Windows operating systems.

Method 4: Formatting USB flash drive

You can choose external storage devices like an SD card, or USB drive to format to the APFS file system. However, keep in mind that, by formatting the flash drive, all the content available in the drive will be lost. Therefore, create a backup of all the contents in the drive that you want to format.

How Long Can A USB Flash Drive Last?

The life expectancy of a flash drive depends on how well you use and store it. If you write data to a USB flash drive, and you store it in a safe place for 20 years, it will work again and all the data will still be intact. But if you use it over and over again, it will eventually wear out.

How Long Can A USB Flash Drive Last

A USB Flash Drive’s life expectancy is also measured by the number of writes or erase cycles made. Once you hit the limit, part of the memory fails to function. This can lead to data losses.

Poor storage of the flash drive can also render it useless. The same can happen when poor-quality materials and components are used in the construction. Overall, a low-quality flash drive fails before its expected lifespan.

Final Words

Well, that is all from me for today! Now you know why your flash drive is so slow on Mac. My honest advice would be to consider the read and write speeds when buying USB flash drives. Fast speed can save you quite a lot of time when copying large files.

If you have many files, videos, or songs you want to carry around with you on a device, getting a USB drive with at least 64GB is reasonable. Hence, you should look for a USB 3.1-supported flash drive if you need the best performance.

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