Your queue will typically be throttled by either rate
& bucket
or by max-concurrent-requests
.
For your backup process to finish in hours instead of minutes, you will need to reduce values drastically, for example by a factor of 15.
You haven't mentioned how long your tasks take to complete, or how many are running concurrently. Suppose some of your tasks take seconds to complete, and others take minutes. Then max-concurrent-requests
will be more useful that rate
& bucket
in directly controlling the maximum number of instances running.