Problem:

• The origin request is from https://jira.magnolia-cms.com/browse/MAGNOLIA-9051

• Slow down of flushing process is reported in https://www.notion.so/magnoliacms/UZH-Performance-Issues-8d058d6acf6a455d9e461ef5cf39749c#8940370091df4137b3cd9a0e8cf5996b

• Additionally. In 6.3: site is isolated out of config, so there is no reason advanced-cache module rely on site changes from site workspace observation to restart cache. See https://git.magnolia-cms.com/projects/ENTERPRISE/repos/advanced-cache/browse/magnolia-advanced-cache/src/main/java/info/magnolia/module/advancedcache/AdvancedCacheModule.java#153

Advantage of creating new flush policy on Public instance:

• don't rely on jcrObservation to invalidate cache -> reduce the number of threads and observation per workspace.