Actually the process 'AAD_Organization_SearchAndCreate_Person_PostSync runs for a long time/a day due to the condition set in field 'AccountToPersonMatchingRule' of the table 'AADOrganization'. The xml code of the field is as below
<?xml version="1.0" encoding="utf-8"?>
<MatchingRules Version="2.0">
<ObjectClass Name="AADUser" OrderNumber="99">
<Or>
<Rule PersonColumn="CentralAccount" ApplyTemplateForPerson="True" AccountColumn="MailNickName" AccountTable="AADUser" ApplyTemplateForAccount="True">
<ValueTemplate>
<ValueTemplate Version="1.0" Name="" />
</ValueTemplate>
</Rule>
<Rule PersonColumn="DefaultEmailAddress" ApplyTemplateForPerson="True" AccountColumn="Mail" AccountTable="AADUser" ApplyTemplateForAccount="True">
<ValueTemplate>
<ValueTemplate Version="1.0" Name="" />
</ValueTemplate>
</Rule>
</Or>
</ObjectClass>
</MatchingRules>
Any alternative to expedite the process?