USB 3 hub transfer speed: how to test it

A drive can feel quick when it is plugged straight into a computer, then slow down through a USB 3 hub. The cause might be the hub, its cable, another connected device, or the drive itself.

Compare the same drive through the hub and a direct port with the USB & SD Speed Test. It measures read and write speed, so you can see whether the hub is affecting transfer performance.

Test the drive through the hub

1. Connect the USB drive or memory card to the hub, then connect the hub to your computer. Use the same drive and cable for every comparison.
2. Open the USB & SD Speed Test. Follow the page's prompts to select the drive and run its read and write checks.
3. Note both results and their units. If the test performs writes, back up important files first and follow any on-screen cleanup instructions.
4. Run the same test again with the drive connected directly to the computer, without the hub. Keep other conditions as similar as possible.
5. Reconnect the drive through the hub and repeat the test once. Compare the repeated results to see whether the difference is consistent.

For a fair comparison, stop other file transfers and avoid running downloads or backups at the same time. If several devices share the hub, disconnect them for the first run, then reconnect them one at a time to see whether one changes the result.

What the result means

The drive is slower through the hub every time

The hub connection is likely limiting performance. The hub's upstream cable, the port on the computer, or the hub's internal connection may be negotiating a slower link. Another possibility is that a device sharing the hub is using some of its available bandwidth. Compare again with the hub empty and with a different upstream cable if you have one.

The drive is about as fast through either connection

The hub probably is not the main cause of the transfer speed you measured. The drive itself may be the limit, especially if it is an older or low-cost flash drive. A browser benchmark also cannot promise that every large file will copy at exactly the same rate.

Read speed is much higher than write speed

This can be normal. Many drives read data faster than they can write it, and some slow down after a fast initial burst. For a large transfer from the computer to the USB drive, write speed matters more. For copying files from the drive to the computer, read speed matters more.

Repeated results vary a lot

Another transfer may be using the hub, the drive may be warming up, or the first write may benefit from a fast cache. Close file-copy windows and other apps using the drive, wait briefly, then repeat the comparison. A single result is not enough to identify a fault.

The test cannot access the drive

Check that the drive is connected and visible to the operating system, then follow the browser's file or folder prompt again. A browser test can measure a selected drive's read and write behavior, but it cannot confirm the hub's advertised USB version or diagnose every hardware fault.

How to fix slow transfers through a hub

1. Stop other transfers. Pause backups, downloads, and file copies while testing. Devices on a hub share its connection to the computer, so simultaneous activity can reduce the speed available to the drive.
2. Check the hub's upstream cable. Make sure the cable between the hub and computer supports the speed you expect and is firmly connected. A USB-C plug shape alone does not guarantee a fast data connection.
3. Try another computer port. Connect the hub to a different port, then test the drive directly in that port. Change one connection at a time so you can tell which change matters.
4. Disconnect other devices from the hub. Test with only the drive attached. If speed improves, reconnect the other devices individually. A webcam, capture device, or another storage drive can compete for the hub's shared connection.
5. Use the hub's power adapter if it has one. Connect the adapter, especially when the hub has several devices attached. A powered hub can supply more power to connected devices, though it does not automatically make a slow data connection faster.
6. Check how the computer sees the connection. In Windows 11, right-click Start, open Device Manager, and expand Universal Serial Bus controllers. On macOS, open System Settings › General › About › System Report › USB. These views can help identify the connected hub or drive, though labels and details vary by computer.
7. Update the computer's USB drivers if the problem persists. Use Windows Update or your computer maker's official support page for the correct driver. On a Mac, install available macOS updates through System Settings › General › Software Update.

Check a real large-file copy too

A benchmark is useful for comparing the hub and direct connection under the same conditions. It is not a complete prediction of a long file copy. The source drive, destination drive, file system, free space, and the drive's sustained write speed all affect the transfer.

For a practical check, copy one large file that you already have backed up, first through the hub and then through a direct port. Use the same source and destination, and compare the elapsed time. If the direct connection remains much faster, replace or bypass the hub or cable. If both connections are similarly slow, the drive or another part of the transfer path is more likely to be the limit.