Why is the write speed so slow to my NAS

Question

Hi, I am trying to improve the write speed from my MBP to the NAS.  I am using the Thunderbolt ethernet adapter connected to an Airport Extreme 7.6.1 using a wired connection. I have a Synology DS213 with a wired connection to the Airport Extreme as well. I am using CAT6 cables.
In testing my performance, I noticed writing files from my MBP to the NAS was very slow; whereas my read performance was much better.  Please see the tests below to explain this further.
Using the Blackmagicdesign Disk Speed Test Utility using a 5Gb test file written to the NAS, I see the following:
Write speed is 7 to 8MB/s  This write speed is what concerns me.
Read speed is between 60 MB/s and 75 MB/s
Using 2 finder windows (drag a file from one window(MBP) to the other(NAS)) and watch the disk activity on the Activity Monitor with a 1Gb file
When writing a file to the NAS from the MBP:
Write speed will burst to 19 to 23 MB/s but it will drop to below 10 MB/s at times.
When writing a file to the MBP from the NAS
Write speed is: 46 to 60 MB/s
Why would the write speed from my MBP to the NAS be so slow ; whereas, the write speed from the NAS to the MBP is very fast.
Synology has 2 WB 'green' disks configured as raid 1.   I understand that part of the influence of writing from the NAS to the MBP is utilzing the advantage of writing to a SSD ; whereas, writing to the NAS it is writing to a slower drive.  
Is 19 to 23 MB/s burst with dips below 10 MB/s during a copy typical?   The other thing is I dont understand why the Disk Speed Utility never records write speeds to the NAS over 10 MB/s whereas the Activity Monitor will show the bursts at times of 19 to 23 MB/s
If 7 to 8 MB/s write speeds is too slow, what can I look at to improve this?  Since writing the file in the other direction is pretty fast considering, how could the issue be a network one?

Answer 1

I was transferring my iPhoto library from an older MBP to a new retina and having the same issue - transfers almost immediately slowing to less than 100k/sec over my beautiful Time Warner-provided WiFi router using regular OSX folder sharing.  I couldn't find any software updates as some other similar threads suggested.
I put my iPhoto library in a .tar.gz archive and that immediately transfered at about 7mb/sec, much much faster!  So, without having diagnosed the issue, perhaps I've uncovered evidence that one or both of my machines doesn't like transferring big file trees.  I bet a zip or any other archive would do the trick.