I'm running SyncBack, the Free version
http://www.2brightsparks.com/download-syncbackfree.html

But most of those tools are pretty good, just take your pick.

The most likely answer to your question: you are using the Windows file copy method, which copies a file and then checks its proper arrival, then it takes the next file. As a result, small files will suffer an enormous overhead without transmission activities, and your transfer speed will drop dead. On top of that, the reported speed is very inaccurate.

While the Windows method is fine for unreliable long distance telephone wiring, it's a nightmare for direct UTP or USB links. Hence, modern sync or backup software offers continuous bitstreams as well, transferring all files in one go while checking in parallel.

In my case, disk transfer speeds (35Mb/s) and the connection (USB3) are the only limits. Performing multiple parallel backup processes from the same HD source or to the same HD destination can slow down the process, as the disk-head has to swap around too much.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though