Arq can restrict the rate at which it uploads data. To set the restriction, open "Preferences" (from the "Arq" menu) and select the "Network" tab.
If you select this option, Arq uploads data at maximum speed unless you are using the network interactively. For example, if you're browsing a web site or watching a video, Arq detects this activity and slows its upload rate.
If you select this option, Arq will not exceed the kilobytes/second you specify when uploading data to S3.
If you select this option, when Arq is using Wifi it will pause itself unless the Wifi network name is checked in the "Select Networks" window.