Information
This option specifies whether SonicWALL UTM security services are applied to maximize security or to maximize performance.
Maximum Security (Recommended) - Inspect all content with any threat probability (high/medium/low). For additional performance capacity in this maximum security setting, utilize SonicOS UTM Clustering.
Solution
Navigate to Security Services->Summary. Set the dropdown for Security Services Settings->Security Service Setting to 'Maximum Security (Recommended)'