Slower Read/Write Speeds Via T-Bolt Hub?

[TMothy]

I recently picked up a Samsung T1 1TB SSD and have been using it plugged directly into my iMac (via USB3.0) and I've been getting 371.2 MB/s Writes and 421.6 MB/s Reads, which seem on par with what I should be getting. [Tested with BMD Disk Speed Test App]

Just to see what would happen, I plugged the SSD into my OWC Thunderbolt 2 Dock (connected to my iMac via TB) and I was only getting 238.3 MB/s Writes and 337.7 MB/s Reads. That's about a 100 MB/s drop! And my question is why? Is the hardware in the dock really slowing it down that much?

 

[Gav2k]

I recently picked up a Samsung T1 1TB SSD and have been using it plugged directly into my iMac (via USB3.0) and I've been getting 371.2 MB/s Writes and 421.6 MB/s Reads, which seem on par with what I should be getting. [Tested with BMD Disk Speed Test App]

Just to see what would happen, I plugged the SSD into my OWC Thunderbolt 2 Dock (connected to my iMac via TB) and I was only getting 238.3 MB/s Writes and 337.7 MB/s Reads. That's about a 100 MB/s drop! And my question is why? Is the hardware in the dock really slowing it down that much?

I'd expect a 10% overhead not 25% that shows the hub is sub par

 

[Fishrrman]

Some docks just can't provide the "full speed" (of USB3) that you get when you connect directly to the Mac's USB3 port.

As Gav2k pointed out, some of this probably is lost "in overhead", some may be lost due to the actual design or chips used within.

Best solution:
Plug the T1 -directly into- the iMac, as you've been doing.