Policy
Specify delay before sending people search request
This policy is used to set the delay for sending people search requests from the Find a Contact box in Outlook and the Related People section that appears in the Backstage view (Info tab) of Office applications. If you enable this policy setting, you can specify the delay in milliseconds between when the user stops (or pauses) typing in the search box and when the application sends a search request. If you disable or do not configure this policy setting, the default delay is 200 milliseconds (0.20 seconds).
cac8f67401e6 L_SpecifyDelayBeforeSendingPeopleSearchRequest Registry
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HKCU\software\policies\microsoft\office\16.0\common\im\presencecontactfastsearchdelayPolicy notes
This policy is used to set the delay for sending people search requests from the Find a Contact box in Outlook and the Related People section that appears in the Backstage view (Info tab) of Office applications. If you enable this policy setting, you can specify the delay in milliseconds between when the user stops (or pauses) typing in the search box and when the application sends a search request. If you disable or do not configure this policy setting, the default delay is 200 milliseconds (0.20 seconds).