USB transfer speed for Windows 7 is incredibly slow to the external drive

I'm running Windows 7 Pro and am try to backup 116 GB of data to my external 1 TB hard drive. My laptop has only USB 2.0 ports and my hard drive is USB 3.0 compatible, as is the cable I'm using. I understand that the transfer speed should still be in accordance with USB 2.0 speeds. However, right now I'm getting 135 KB/s and it's been gradually dropping. For an earlier transfer, I would get between 4 MB/s to 8 MB/s. So, I'm really just wondering what's going on with my transfer rate and what I can do to improve it. I'm currently about 35 GB into the 116 GB transfer.

Another strange thing is that the window which shows the transfer status decided to max out at 835 MB, and therefore shows items remaining as 0. However, it is still performing the rest of the transfer, and I can see it still cycling through files.

Now that I think about it, it seems plausible that the speed being shown by the window is calculated merely as total data transferred / time elapsed. Since the "counter" of data, as far as what is being displayed in the window, maxed out at 835 MB, as time increases, the speed shown is going to keep decreasing because the 'total data transferred' value isn't being incremented.

So with that in mind, I suppose I don't actually know at what rate the data is being transferred currently. Nonetheless, my best speed earlier was only around 8 MB/s. Shouldn't USB 2.0 deliver closer to 35 MB/s? Also, if someone can tell me why the transfer status window is displaying the incorrect data information and how to fix this, that would also be appreciated.