Computer Configuration > Administrative Templates > Firefox > Content Analysis (DLP)
Both
HKLM\Software\Policies\Mozilla\Firefox\ContentAnalysis
If this policy is enabled, you can specify the timeout in number of seconds after a DLP request is sent to the agent. After this timeout, the request will be denied unless 'Default Result' is set to 1 or 2. If this policy is disabled or not configured, the timeout is 30 seconds.