Drobo S gen 2 - Performance Question

Older product question - Drobo S Gen 2 model, all 5 bays, most are 2TB HDD and 4TB HDD.

USB 3.0 connection from iMac late 2012 model to Drobo. iMac only has USB 3.0 usb ports.

Using Blackmagic Design Disk Speed Test application from Mac App Store, the write / read times to Drobo are 84.5mbs and 75.6 mbs.

Running same test using the internal iMac HDD the w/r results are 128.3mbs and 292.4 mbs. I was / am expecting higher performance for a USB 3.0 storage device than what I am receiving now.

Drobo Tech support confirmed that this model supports USB 3.0. All of the HDD in the Drobo are within 2 years old or newer - I would be surprised if the disk speed itself is causing the performance delays.

Anyone have this model and can comment on their performance results using this tool or similar performance tool? I am doing more video editing using Final Cut Pro X - it works, but I would like to have less lag in the editing process.