The "some channels" slowness was to a large degree due to suboptimal code in Erratafactory.publishToChannel(), when dealing with cloning of cloned-channels. spacewalk.github: 7da7fd59d23e1f1d45a996d6b0f18bd04a8deeae
Spacewalk 2.5 was released.
This BZ closed some time during 2.5, 2.6 or 2.7. Adding to 2.7 tracking bug.