Performance/Admin Page Access - Does available disk space affect access to the ReadyNas

Ok, mine aren't so bad now I guess.  After disabling the journaling, I get this:

NAS performance tester 1.7 http://www.808.dk/?nastester
Running warmup...
Running a 400MB file write on \\nas\backup 5 times...
Iteration 1:     17.77 MB/sec
Iteration 2:     18.23 MB/sec
Iteration 3:     18.23 MB/sec
Iteration 4:     18.23 MB/sec
Iteration 5:     18.22 MB/sec
-----------------------------
Average (W):     18.14 MB/sec
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Running a 400MB file read on \\nas\backup 5 times...
Iteration 1:     16.82 MB/sec
Iteration 2:     21.37 MB/sec
Iteration 3:     18.25 MB/sec
Iteration 4:     18.64 MB/sec
Iteration 5:     16.58 MB/sec
-----------------------------
Average (R):     18.33 MB/sec
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Disabling the journalling definitely helped with the speed.  I unchecked "optimize for OSX but performance took quite a hit with similar performance to when my network link was 100Mbps.  I reenabled it and performance was restored.

We've had the NAS for a few years now so the volume itself has been created a while now.  I have replaced both of the disks of the NAS and I'm not sure whether it has the larget block size.  I normally empty the NAS on a Friday to prepare for full backups on the weekend.  I have some other stuff I will copy off as well, then do a factory reset.  It is running 4.1.14 which it says is the latest version available for this device.  How long does a factory reset take to perform?  I have 2 1TB drives installed in Raid 1.

Thanks.