The following graph shows the overall performance of the NAS in all tests we conducted using our custom-made software.
The DS214se performed pretty well in both RAID configurations and in single-disk mode, even compared to significantly more expensive NAS servers. However, it performed poorly in our external-storage tests since it doesn't provide USB 3.0 support, which is a great shame as its performance would have been a lot better had Synology only provided a faster USB 3.0 port. The performance provided here is definitely good if you don't use external drives, especially considering the price.
Let us now compare the DS214se's performance to that of other NAS devices.