Ran the less time consuming test steps from above. For 100+ repos and 2 capsules sync, it took 29.59s for one capsule and 32.58s for the other. Tested on 6.4.3_2.0.
Marking issue as verified.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2019:0903