According to Splunk’s Enterprise Security (ES) Installation and Sizing Guide, the majority of processing and computational load generated by the Splunk App for Enterprise Security is concentrated on the Search Head(s).

This is because Splunk ES is built around a search-driven correlation model — it continuously runs scheduled correlation searches, data model accelerations, and notables generation jobs. These operations rely on the search head tier’s CPU, memory, and I/O resources rather than on indexers. ES also performs extensive data model summarization, CIM normalization, and real-time alerting, all of which are search-intensive operations.

While indexers handle data ingestion and indexing, they are not heavily affected by ES beyond normal search request processing. The Cluster Manager only coordinates replication and plays no role in search execution, and Heavy Forwarders serve as data collection or parsing points with minimal analytical load.

Splunk officially recommends deploying ES on a dedicated Search Head Cluster (SHC) to isolate its high CPU and memory demands from other workloads. For large-scale environments, horizontal scaling via SHC ensures consistent performance and stability.

References (Splunk Enterprise Documentation):

• Splunk Enterprise Security Installation and Configuration Guide

• Search Head Sizing for Splunk Enterprise Security

• Enterprise Security Overview – Workload Distribution and Performance Impact

• Splunk Architecture and Capacity Planning for ES Deployments