In the Confluence 6.6 beta release notes it claims
We’ve made some changes to reduce the CPU and memory load of actions that search for users, for example mentioning someone, sharing a page, and selecting a user in a blueprint field or macro parameter.
Would someone from Atlassian be able to shed more light on the actual changes that have been made here? Will these updates flow through to add-ons that are using the search API to find users already for their own functionality? Is there some new best practices we should be using when searching for users or groups (particularly with the large instance data centre compatibility in mind) ?