You can monitor Retrospect’s network usage to understand the bandwidth usage compared to the speed test.
Windows: Open Task Manager and click on the Performance tab for Retrospect.
Mac: Open Activity Monitor and select Networking or use a third party tool like iStatMenu.
Retrospect’s current architecture prevents simultaneous backup and cloud upload, so you will see the network usage drop after each RDB file is uploaded while the next one is filled with data. This delay should only be between 15 and 60 seconds, depending on the internal network and hardware involved. You can see those gaps in the screenshots above. With a 6 Mbps upload link, this drop in performance will lead to a 5% reduction in the maximum bandwidth usage.