When handling a WMS 1.3.0 GetCapabilities request with JDBC Configuration enabled, the database has to be queried multiple times per layer and layer group to load the WMS service configuration. This is a relatively inefficient query that actually loads all of the services (WCS, WFS, WMS, etc.) and then returns the desired service. The other core OGC GetCapabilities requests (WCS 1.0, WCS 1.1, WCS 2.0, WFS 1.0, WFS 1.1, WFS 2.0, WMS 1.1) all store a local instance of the service configuration that is used throughout the handling of the request and WMS 1.3.0 should be updated to do the same.
The WMS 1.1.1 GetCapabilities was actually updated to do this specifically to support JDBC Configuration:
The WMS 1.3.0 GetCapabilities is also the only one that has to load its data from the catalog twice. This causes a more significant performance impact when the Hazelcast Clustering module is also being used.